SB U. S. DEPARTMENT OF AGRICULTURE, BDREAU OF ENTOMOLOGY— BULLETIN No. 107. L. O. HOWARD. Enlomolosut and Chief of Bureau. RESULTS OF THE ARTIFICIAL USE THE WHITE-FU?sTtUS DISEASE IN KANSAS: WITH NOTES ON APPROVED METHODS OF FIGHTING CHINCH BUGS. OF FREDERICK H. BIIAINGS, Associatt' Fro/fnnor of Bold ni/ and Bncferiology, A XI) PRESSLEY. A. GLENN, Ass-istant I'rofeasor of Entohioloyy, University of Kansas. lasuED Decembeu 21, 1911. WASHINGTON: GOVERNMENT PRINTING OFFICE, 1911. Qass SDf; - U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF ENTOMOLOGY— BULLETIN No. 107. *-.- ^ ^ L. O. HOWARD, Entomologi.t and Chief of Bureau. >''^ RESULTS OF THE ARTIFICIAL USE OF THE WHITE-FUNGUS DISEASE IN KANSAS: zJt} fsn WITH NOTES ON APPROVED METHODS OP FIGHTING CHINCH BUGS. FREDERICK H. BILLINGS, Associate Professor of Botany and Bacteriology, AND ^^ PRESSLEY A.'gLENN, Assistant Professor of Entomology, University of Kansas. Issued December 21, 1911. WASHINGTON: GOVERNMENT PRINTING OFFICE. 1911. CvJ^"^ <> rrp v'v 'iV.9 LETTER OF TRANSMITTAL IT. S. Department op Agriculture, Bureau of Entomology, Washington^ D. 6'., August 17, 1911. Sir : I have the honor to transmit herewith for publication a manu- script entitled " Results of the Artificial Use of the "Wliite-Fungus Disease in Kansas: With Notes on Approved Methods of Fighting Chinch Bugs," by Frederick H. Billings, associate professor of botany and bacteriology, and Pressley A. Glenn, assistant professor of ento- mology. University of Kansas. The chinch-bug situation having become serious in Kansas, pro- vision was made by the University of Kansas for the distribution of insects infected with the white fungus, S porotrichum glohuliferwm. The results of this work are embodied in the following pages, and I recommend the publication of this manuscript as Bulletin No. 107 of this bureau. Respectfully, C. L. Marlatt, Acting Chief of Bureau. Hon. James Wilson, Secretary of Agriculture. PREFATORY NOTE. The chinch-bug situation having become serious in Kansas in 1909, provision was made by the University of Kansas for the distribution of diseased insects during the season of 1910 in accordance with the plan inaugurated by Dr. F. H. Snow during the nineties. The effi- cacy of this method of combating chinch bugs, however, has been questioned, not only by local investigators who gathered the field data for Dr. Snow's later reports, but by observers in other States, where, in most instances, the practice of distributing diseased bugs has been discontinued. While the demand of Kansas farmers for diseased bugs was granted, steps were taken to conduct an investigation of the problem of artificial distribution, not from the standpoint of proving or disproving Dr. Snow's theories as carried out in the nineties, but rather from the standpoint of practicability under present conditions. The investigation was placed in charge of the writers, who began work in January, 1910, for the purpose of definitely settling the ques- tion as to the utility of continuing the work of artificial infection. It was felt that the seriousness of the situation to the farmers merited a stand that was based on many carefully collected data, so that future efforts might be urged along lines shown to be most efficient. The writers of this bulletin wish to express their appreciation to Chancellor Frank Strong, whose continued interest in the investiga- tions made them possible ; to Profs. Stevens and Hunter for helpful suggestions; to Prof. Barber for the report of his work on chinch- bug inoculation ; to Messrs. Leslie Kenoyer and Otto OpoUo for their faithfulness in conducting experiments and taking observations near their respective homes ; and to Messrs. E. O. G. Kelly, L. A. Kenoyer, and W. C. Bower for collecting weather data. Frederick H. Billings. Pressley a. Glenn. University or Kansas. 4 CONTENTS. Historical summary of chinch-bug diseases 7 Results of experiments for 10 years, 1888 to 1897 10 Outline of work against the chinch bug carried on in Kansas diu-ing 1910 14 Natural distribution of Sporotrichum in Kansas 16 Natural presence of Sporotrichum among chinch bugs during hibernation 17 Natural presence of Sporotrichum in wheat fields and cornfields during the spring and summer of 1910 18 Insects upon which Sporotrichum has been found 20 Natural distribution of Sporotrichum in the soil and its relation to artificial infection 20 Artificial infection experiments with Sporotrichum in the laboratory 21 Artificial infection — field experiments 26 Mr. L. A. Kenoyer's report of hia experiments with Sporotrichum and the chinch bug 35 Remedial measures and conclusions 43 Bibliography 54 ILLUSTRATIONS. PLATES. Page. Plate I. Sterile jars filled with soil and chinch bugs, showing diseased bugs resulting from a spontaneous outbreak in the jar 16 II. Fig. 1. — Chinch bug enveloped in growth of the white fungus (Sporo- trichum globuliferum) . Figs. 2-7. — Dead chinch bugs, showing various degrees of envelopment in the white fungus 16 III. Various insects killed by the fungus diseases Isaria sp. and Sporotri- chum globuliferum 20 IV. Various insects killed by the chinch-bug iuiigns,Sporotrichum globu- liferum 20 V. Fig. 1. — Patch of corn protected by the oiled-straw barrier. Fig. 2. — Cornfield showing corn treated with crude oil 52 TEXT FIGURES. Fig. 1. Map of Kansas, showing the number of packages of diseased chinch bugs sent out in 1910 by the University of Kansas to the different counties in the infested area 15 2. Map of Kansas, showing all the localities where Sporotrichum was found as a natural infection. 19 3. Diagram illustrating the construction of the dust barrier 48 4. Diagram illustrating the oiled-ridge type of barrier 50 6 RESULTS OF THE ARTIFICIAL USE OF THE WHITE-FUNGUS DISEASE IN KANSAS, WITH APPROVED METHODS OF FIGHT- ING CHINCH BUGS. Historical Summary of Chinch-Bug Diseases. Since Dr. Snow, in his First and Sixth Reports of the Experiment Station of the University of Kansas, has given a somewhat extensive account of the chinch-bug disease prior to 189G, only a brief historical summary is deemed necessary in this bulletin. Three chinch-bug diseases have engaged the attention of entomolo- gists — a bacterial disease and two fungous diseases. Wliat was at first supposed to be a bacterial disease was, on further investigation, ascertained to be only a normal condition in healthy bugs, so the two fungous diseases are the only true ones which have received attention. One of the fungous diseases is due to a parasitic fungus, known to science as Empusa aphidis^ and popularly known as the gray fungus, since it envelops the dead bug in a gray covering; the other is due to another parasitic fungus, known to science as SporotHchum globu- liferum and commonly known as the white fungus, since it envelops the dead bug in a white cottony mass. The latter is of special interest to us since it is the one which has been under investigation in Kansas. The chinch bug was first noticed in North Carolina in ITSS,*^ In the Mississippi Valley it has been known since 1823.'' Since 1840 it has been under constant observation in Illinois and other States. It proved such a destructive pest from the first that entomologists have diligently sought for effective remedies by which its depredations could be avoided. The first evidence of disease among chinch bugs was noted by Dr. Henry Shimer at Mount Carroll, 111., in ISGS.^' According to Dr. Shimer's notes, this outbreak was first noticed on low creek-bottom land, spreading gradually to the higher localities. The disease attacked both the old and the young, and was at its maximum during the moist, warm weather that followed the cold rains of June and the first part of July of that year. So complete was the destruction of the bugs that he wrote on August 8 : Scarcely one in a thousand of the vast hosts of young bugs observed in the middle of June yet remain alive, but plenty of dead ones may be seen every- " Fitch's Noxious Insects of New York, 1865. " Dr. Porbes's Insect Life, vol. 1, No. 8, p. 259. " See Bibliography, p. 54. 8 THE WHITE-FUNGUS DISEASE IN KANSAS. where lying on the ground, covered with the common mold of decomposing ani- mal matter, and nothing else, even when examined by the microscope. Even of those that migrated to the cornfields a few weeks ago in such numbers as to cover the lower half of the cornstalks, very few are to be found remaining alive; but the ground around the base of the corn hills is almost literally cov- ered with their moldering, decomposing bodies. This is a matter of so common occurrence as to be observed and often spoken of by the farmers. They are dead everywhere, not lying on the ground alone, but sticking to the blades and stalks of corn in great numbers, in all stages of development. Entomologists were slow to accept Dr. Shimer's theory of an epidemic disease. AValsh and Riley ridiculed the idea, and Le Baron six years later declared that he knew of no predaceous parasitic enemies of the chinch bug. Later observations, however, confirmed the accuracy of Dr. Shimer's observations. Evidence of disease among chinch bugs was not again reported until 1882, when Dr. S. A. Forbes, of Illinois,^^ and Prof. Popenoe, of Kansas,^^ both reported localities in their respective States in which the bugs were dying with a fungus disease which embedded the dead bugs in a growth of white mold. In August of the same year Dr. Forbes discovered what he thought was a bacterial disease due to a bacillus which he found in great num- bers in the alimentary canal of dead bugs ; ^^ but after a thorough in- vestigation, which extended through several years, he ascertained that the presence of the bacillus was a normal condition in the alimentarj^ canal of healthful chinch bugs,^^ and the theory of a bacterial disease was abandoned. The fungus disease noted by Dr. Forbes and Prof. Popenoe was what is commonly known as the gray fungus, Empiisa aphidis. AVhat fungus was responsible for the disease among the bugs reported by Dr. Shinier can not be ascertained. The white fungus had not yet been detected. This fungus was first observed by Dr. Forbes in Clinton County, 111., July 7, 1887, and again on August 7, 1888.''« ^^ For more than a year this fungus affection was not found among chinch bugs, although a close watch was kept for it, but August 7, 1888, it was seen at Flora, in Clay County, fastening dead bugs to leaves of corn. Almost simultaneously it was reported from Minnesota,^^ lowa,^^ Ohio, and Kansas.^'^ It is worthy of note that no evidence of disease among chinch bugs was noted for about 80 years after the chinch bug became known as a serious pest, and it was 100 years after its first appearance that the white fungus was definitely recognized. It is also all the more re- markable in view of the prevalence of the disease over such a wide area at this time and during the years following. If these diseases were present among the bugs from the first, it seems strange that they were not detected earlier, and if they were in the process of in- troduction it seems strange that almost simultaneously they should be so plentiful in so many different, widely separated localities. It HISTORICAL SUMMARY OF DISEASES. 9 is probable that they were present from the first^ but because of the fact that they are so dependent upon the abundance of their host and upon favorable weather conditions they are not conspicuous except at intervals when conditions are just right. In the years immediately following the discovery of the white fungus much attention was given to the investigation of chinch-bug diseases. Dr. Lugger, of Minnesota, was the first to attempt to disseminate the disease by the distribution of diseased bugs. In October, 1888, he sent diseased bugs to various localities, and the experiment was apparently successful, as the bugs in these localities were found to be dying with the disease a little later. But the disease spread so rapidly that Dr. Lugger was led to suspect very strongly that the spores of the disease were already in these localities and that he had only reintroduced them, the spread of the disease being due to the spores that were already there rather than to the spores which he introduced.^^ ^^ Dr. Snow's observations and experiments in Kansas began in 1888 and extended through the season of 1896. In 1888 the chinch bugs disappeared from some of the eastern counties of the State during the months of May and June, and Dr. Snow expressed the belief that they were carried off by an epidemic.^^ Experimenting with the gray fungus, Empusa aphidis^ he found that the disease could be communicated from diseased bugs to healthy ones by confining healthy bugs with the diseased ones. He also sent some diseased bugs to farmers and to agricultural experiment stations in Nebraska, Iowa, Missouri, Minnesota, Michigan, Indiana, Illinois, and Kentucky. The reports received from those who received the diseased bugs were very encouraging."® In 1890 chinch bugs in Kansas were very scarce, having been very generally exterminated in 1889. In 1891 the legislature established an experiment station at the University of Kansas " to propagate the contagion, or infection, that is supposed to be destructive to chinch bugs, and furnish the same to farmers free of charge, under the direction of the chancellor, F. H. Snow." During this period between 40,000 and 50,000 packages of the fungus were sent out to farmers, and extensive experiments were carried on in the laboratory and some in the field ; the life history of the white fungus was worked out, and the best means of propagating it in large quantities ascertained. Observers were sent out from the station at various times to make observations in the field. The reports of these observers in 1891 and 1892 were very favorable, but in succeeding years the results of the observations were less favorable and brought to light the probability that the fungus was widely distributed naturally, since it seemed to be the rule rather than the 10 THE WHITE-FUNGUS DISEASE IN KANSAS. exception that the fungus was working as effectively in fields where none had been introduced as in fields where it had been artificially distributed. The fungus was found in every locality where the inspectors made observations. In commenting on this fact, Dr. Snow said : ^^ Whether this widely extended natural presence of the Sporotrichum was the result of the general introduction of the infection throughout the State, in 1894, from the laboratory of this station it would not be possible with certainty either to affirm or deny. A full account of Dr. Snow's work will be found in his six reports of the experiment station of the University of Kansas for the years 1891, 1892, 1893, 1894, 1895, and 1896. The following is taken from his last report : RESULTS or EXPERIMENTS FOR 10 YEARS, 1888-1897.^^ 1. Chinch bugs in any of their stages of development scarcely run the slightest risk of death on account of heavy rains, even when these are of long duration. They are inconsiderably affected by extremes of heat and cold. 2. We know of no contagious bacterial disease of the chinch bug. 3. There are two parasitic, contagious, fungoid diseases that kill chinch bugs, namely, Sporoirichum glohuliferum ("white fungus") and Empusa aphidis ("gray fungus"). 4. These two diseases show their greatest virulence where the ground is damp and shaded from the direct rays of the sun and the air is humid. 5. We do not know to what extent the spores of these diseases are normally present in any given region. When they are present, whether naturally or artificially introduced, and the weather conditions are as given above, and the bugs are massed together, an outbreak of the diseases will occur. The number of chinch bugs killed in any field is approximately proportionate to the number of bugs in the field. 6. Sporotrichum can be artificially communicated to healthy chinch bugs, (a) It attacks bugs of all ages, but the older the bug the more easily does ii succumb. (&) Bugs of any age that have been weakened from any cause, or injured, fall more easy victims to the disease than do those individuals that are in perfect condition, (c) The adults of the second brood, which, in the ordinary course of events, winter over and lay the eggs for the brood of the succeeding spring, are much more successful in resisting the disease than are the adults of the first brood, (d) The fungus is not active in winter, and, though it be present with the bugs in their winter quarters, they do not die of it, even though the winter be as mild and humid as was that of 1895-96. The chinch bug seemed to have been almost exterminated in 1896 and there has not been any widespread outbreak since until the last two years, and hence little opportunity to investigate the practical value of the use of Sporo- trichum until this year. Many requests for the fungus were received at the university last year, but no provision was made by the university to supply it until this year. WORK IN OTHER STATES. The method of combating chinch bugs by the artificial distribution of infection has been extensively used in other States, but in most cases the practice has been abandoned. HISTORICAL. SUMMARY OF DISEASES. 11 Dr. Lugger, who first attempted to disseminate the disease by- means of distributing diseased bugs in 1888, adopted the plan again in 1895. In the First Annual Eeport of the State Entomologist of the State Experiment Station of Minnesota for the year 1895, he says: Judging from the large number of letters, the writers were well pleased with the results of spreading spores among chinch bugs. * * * Of course it would be folly to claim that the disease was always spread by the introduction of such spores, and it is also possible that it would appear simply because the climatic conditions were in its favor. Whatever may be the reasons for its appearance, so many farmers believe in the effectiveness of introducing spores causing the disease that the State can well afford to continue this work. However, the practice has been abandoned in Minnesota. Prof. F. L. Washburn, State entomologist, in Bulletin No. 77, Agricultural Experiment Station, 1902, says: We do not know of any profitable means of killing the chinch bugs in the grain at present. In this connection we will say that the sending out of dis- eased chinch bugs has been abandoned, it having been found that the results were not sufficiently practical. Dr. S. A. Forbes, who first definitely recognized the white fungus in 1887, began an extensive series of experiments with this and also the gray fungus, which lasted till 1896. The results of his investi- Sfations were not such as to lead him to recommend the use of the fungous diseases as a means of combating chinch bugs, although he was not ready to declare the method a failure. By isolating bugs sent in by farmers, he found that the disease developed among a large percentage of them without their being inoculated, and thus was led to conclude that the disease was very generally distributed naturally. In a series of field experiments he found that the disease was as prevalent in fields in which the fungus had not been introduced as in the fields in which it had been thoroughly distributed. Accounts of these experiments are recorded in the Sixteenth, Seventeenth, Eighteenth, Nineteenth, and Twentieth Reports of the State Ento- mologists of Illinois, 1888-1896. In the Twentieth Report he says: Whether the fungi of contagious diseases can be artificially made use of to hasten or intensify the serviceable effect of favorable weather with a frequency or to an extent to make this procedure economically worth while, I am not yet prepared to say. The methods of distributing these fungi in the fields have hitherto been too crude to make their substantial failure conclusive as to the whole subject. It now seems quite clear that they can be at the best only used as a secondary to other measures, especially the midsummer measures described in the third article of this report. If applicable at all, however, they can be brought to bear at a point now entirely defenseless, and it seems the duty of American economic entomologists to spare no pains to investigate to a final and indisputable conclusion which promises so much as a remote possi- bility that the chinch bug may be attacked even to occasional advantage after it has settled itself in fields of small grain. 12 THE WHITE-FUNGUS DISEASE IN KANSAS. In Nebraska the fimgiis was used extensively in 1893, 1894, and 1901, but in the outbreaks of 1909 and 1910 the fungus was not recom- mended. To those asking for the fungus a circular was sent, which says in part: It seems that the usefulness of this fungus disease as a method of destroy- ing chinch bugs has been greatly overestimated by the farmers, since the ex- periments with it show that it spreads only when the weather conditions are just right — that is, when the temperature is somewhere between 70° and 80° F., and the air is very humid, and when bugs are massed in sufficient numbers that they come in contact with each other. When such conditions exist, the disease spreads rapidly and destroys the bugs very effectively, but under other conditions, especially in dry weather, the disease is quite ineffective. It is be- cause of this extreme imreliability of the chinch-bug fungus disease, and its failure to spread when most sorely needed, that we have come to regard it as more of a detriment than a benefit in many cases, since it causes the farmer to place confidence in an unsafe measure to the neglect of more practical, though also more laborious, means of control. The fungus was also used in Missouri, but has been discarded. Prof. J. M. Stedman" says: A great many people send in to this office in the spring of the year for the chinch-bug disease, with the idea of scattering this disease about the fields of wheat and killing the chinch bugs infesting them. It is a fact that under cer- tain climatic conditions this chinch-bug disease * * * -^^n jjj^j ^ great number of chinch bugs. But from seven years' experience with this disease in the wheat fields throughout the State of Missouri I am firmly convinced that the artificial use of this disease by the far)ners of Missouri does very little, if any, good. * * * in the first place the chinch-bug disease is a natural one, found in nature, and is not an artificial one. * * * * * * If the chinch bugs are in large numbers and the weather is hot and very moist, these spores will germinate on the bugs, and the fungus plant will kill them in great numbers. But if the weather is hot and dry, or too cool, although it may be moist enough, then the spores will not germinate, and no agriculturist has the power to bring about the proper conditions in his wheat or cornfield that will enable them to germinate. * * * * * * I wish to say that it is very doubtful whether there is a wheat field or a cornfield in Missouri that does not naturally contain spores of this disease. I have been impressed with this fact evei-y summer, because almost invariably, when the person applying for the chinch-bug disease sends to this office living chinch bugs that have been placed, as they should be, in a tin box containing no dirt, but some green vegetable matter, as for instance, pieces of gi'een corn, wheat, or grass, and the box closed up as it should be, perfectly tight, thereby generating moisture in the box from these green vegetables, that by the time these bugs reach me the box contains more diseased fungus-covered bugs than we return ; thus showing that the spores were already there in his field. * * * Knowing these facts, I can do no other than to conscientiously advise the farmers of Missouri not to trouble themselves with obtaining and scattering this disease about their fields, but to rely entirely, as they will ultimately have to do, upon nature to bring about the proper climatic conditions for the de- velopment of this disease in their fields. " Bulletin No. 51, Agr. Exp. Sta., University of Missouri, July, 1902. HISTORICAL SUMMARY OF DISEASES. 13 Prof. F. M. Webster was one of the first to interest himself in the investigation of the fungus. As a special agent of the United States Department of Agriculture, located at La Fayette, Ind., he conducted some experiments which showed that moisture and a large number of bugs are essential factors in the successful propagation of the dis- ease.'® Later, as State entomologist of Ohio (now connected with the U. S. Bureau of Entomology), he experimented with the fungus in Ohio in 1895 and 1896. As 1895 was a dry season the fimgus proved ineffective ; but in 1896 the weather conditions were favorable, and Prof. Webster states : "^ »' I have always held to the opinion that the parasitic fungus Sporotrichum globuliferum could only be used in a manner to effect relief to the farmers dur- ing wet seasons and where there was a superabundance of host insects * * *. This year (1896) I can say with all conditions favorable, Sporotrichum globuli- ferum has done all that Dr. Snow or any other entomologist claims for it, but under conditions as adverse as these have been favorable the results will prove quite the reverse. It would seem that Prof. Webster's subsequent observations have not materially changed his views ; for he states in November, 1909 : * As the fungus has many other host insects, it is probably present to a greater or less degree throughout the country every year. There is no doubt that during wet weather considerable benefit may be derived from the artificial cultivation and application of this fungus, but its efliciency is very dependent upon this meteorological condition, and, as has already been shown, chinch bugs develop in greater abundance in dry seasons. It will thus be seen that only during unusual seasons, that is to say, seasons that have been very dry while the chinch bugs were hatching from the egg, but wet afterwards, can satis- factory results be expected from this measure. Thus it appears that the use of the fungus has not come into gen- eral use as a means of combating the chinch bug. Its use has been abandoned in nearly every State that has given it a good trial. Only three States sent out fungus during that season — Oklahoma, Ohio, and Kansas. Dr. Gossard, of Ohio, questions very seriously the wisdom of sending out the fungus and our investigations in Kansas this season, as the report shows, have made it certain that in Kansas at least the artificial distribution of the fungus is unnecessary. Its failure to come into general use may be ascribed to the following reasons : 1. The disease proves effective only during unusually wet seasons and when the bugs are very plentiful. 2. The disease is quite generally present in the field naturally. 3. Dependence on the fungus leads farmers to neglect other more practical means of control. « Circular No. 113, Bur. Ent., U. S. Dept. Agr., 1909. 14 THE WHITE-FUNGUS DISEASE IN KANSAS. Outline of Work against the Chinch Bug Carried on in Kansas DURING 1910. Owing to the presence of chinch bugs in destructive numbers over a considerable portion of the State in 1909, many requests were re- ceived for diseased bugs. The demands l3ecame so insistent that the regents of the University of Kansas made provisions for supplying the fungus to all applicants during the season of 1910. Following the methods used by the late Dr. Snow, a package of diseased bugs, accompanied by the necessary literature, was mailed to each appli- cant. The mailing list was primarily for residents of Kansas, but a number of farmers in Oklahoma were supplied with the fungus. The literature consisted j^rincipally of a four-page folder, which contained, besides information for the use of the fungus, other infor- mation which was designed to enable the farmers to make intelligent observations in their own fields and to avail themselves of other methods of fighting chinch bugs. It was understood that many authorities do not advocate the arti- ficial use of Sporotrichum ; still, in the absence of conclusive evidence to prove its impracticability, the recommendations of Dr. Snow in his last report were followed, with the hope that in the face of a threatened chinch-bug epidemic some good might result. At the same time, however, provision was made for an investiga- tion in order to determine definitely whether or not artificial infec- tion accomplishes results sufficient to justify the labor and expense involved. Work began early in 1910, some months before any infection was sent out. It was necessary to determine early which portions of the State were suited for carrying on experiments, judging from the number of bugs, and the extent of the distribution of the fungus naturally in the soil. Data as to the distribution of the fungus were regarded as more nearly conclusive if obtained before artificial dis- tribution began. No Sporotrichum had been distributed in Kansas since Dr. Snow distributed it from 1891 to 1896. Dr. Snow's reports show that the fungus was very generally present in the fields in 1895 and 1896, and on that account results derived from its artificial distribution were of doubtful benefit. This was thought to be a very favorable time for determining if the fungus had meanwhile maintained itself in the fields. Whether or not the fungus found in the soil at that time was the result of that sown by Dr. Snow years ago is, however, not pertinent to the problem, since the problem concerns itself with a plan of action for the present and future. OUTLINE OF WORK AGAINST CHINCH BUG. 15 In comparing the First Annual Keport of Dr. Snow for 1891 with the last one for 1896, we find statements which would lead us to believe that the artificial distribution of the disease had at least the is y effect of increasing the amount of Sporotrichum, even if we doubted its first introduction into Kansas in the nineties. In the report of 1891 we read : It must be remembered that tbese contagious diseases of the chinch bug are naturally present in certain portions of the Mississippi basin during every 10944°— Bull. 107—11 2 16 THE WHITE-FUNGUS DISEASE IN KANSAS. year, and become epidemic over large portions of this area in occasional years. The object of my experiments has been to artifically introduce the disease at times when they are not naturally raging in the fields. It was found in 1891 that there was no evidence of a natural existence of the three diseases in any part of the State of Kansas. This statement is abundantly substantiated by the detailed report of my field agent. Mr. Hickey, and by the reports of many farmers. In his final report Dr. Snow makes this comment : While no such general epidemic of Siwrotrichum was noted in this year (1896) as occurred in 1895, yet the disease seemed present in those parts of the State visited, wherever favorable conditions existed, and in the fields, whether artificially infected or not. It was therefore doubtless true that in the later years of Dr. Snow's campaign many spontaneous outbreaks occurred, and that condition's were perhaps not widely diflPerent from what they are to-day. Owing to a lack of scientific data, however, there is room for doubt as to the absence of Sporotrichiun from Kansas soil prior to the recorded observations in 1891. The investigations summarized in this paper had chiefly to do with the following problems: 1. Extent to which the white fungus disease of the chinch bug is naturally present in Kansas soil. 2. Practicability of artificial infection of fields in which the fungus disease is found to be naturally present. 3. Practicability of artificial infection of fields in which the fungus disease is shown to be scarce, or at least ineffective. 4. Experiments with barriers and insecticides. Among other matters considered were (1) laboratory methods of propagating Sporotrichum ; (2) artificial inoculation of chinch bugs with spores. Natural Distribution of Sporotrichum in Kansas. In any investigation to determine the efficacy of artificial infec- tion of a field with a. parasitic fungus, the presence or absence of the fungus is one of the first points to be determined. If its ab- sence be proved, a widespread persistent application of the infec- tion might result in a considerable mortality of bugs, provided, of course, they are numerous enough to spread the contagion among themselves ; but if the presence of the fungus is shown to be general, the problem resolves itself into that of attempting to improve natural conditions by artificial ones. Theoreticallj^, at least, such a thing would be possible, but its practicability must be determined by actual experiment under a variety of conditions. It would have to be shown that enough bugs, beyond what naturally would have died, succumbed to the artificially sown fungus to make the effort worth while. Bui. 1 07, Bureau of Entomology, U. S. Dept. of Agriculture. Plate I. Sterile Jars Filled with Soil and Chinch Bugs, Showing Diseased Bugs Resulting from a Spontaneous Outbreak in the Jar. (Original.) The white spots in the jars are fungus-covered bugs. Bui. 107, Bureau of Entomology, U. S. Dept. of Agriculture. Plate II. Fig. 1.— Chinch Bug Enveloped in Growth of the White Fungus Sporotrichum globuliferum. From Photomicrograph Enlarged X 22. (Original.) Figs. 2-7.— Dead Chinch Bugs, Showing Various Degrees of En- velopment in the White Fungus. From Photographs Enlarged X 7. (Original.) NATURAL PRESENCE DURING HIBERNATION. 17 A spontaneous outbreak of the fungus in a field into which no fungus had been introduced would imply its natural presence there; and, conversely, its natural presence there would imply that a spontaneous outbreak would be possible, if given proper conditions. Hence it was determined to visit representative counties distributed through the infested area, and by examination of fields taken at random ascertain to what extent Sporotrichum is present in Kansas soil. Natural Presence of Sporotrichum among Chinch Bugs during Hibernation. As conditions for the development of the chinch-bug disease were not favorable while the bugs were in hibernation, partly because of the cold or cool dry weather that prevailed and partly because of the resistant state of the insects, it was necessary to collect them and bring them into warm, moist surroundings, where^ with increased activity, without food, their vitality would be diminished sufficiently for them to succumb to the attack of the disease. The type of collecting jar adopted was an 8-ounce square bottle with wide mouth and metal screw top lined with cork. This was light in weight and packed well in a carrying case. Before taking a lot of bottles from the laboratory they were thoroughly sterilized in an autoclave. The tops were left loose during sterilization and then screwed down tightly upon removal, while hot, from the sterilizer. After placing a number of bugs and a small quantity of earth in a bottle, by the use of sterilized tools, the lid was screwed down tightly and not removed until the bugs were dead, unless the soil in the bottle was too dry, in which case a little water was added, either from a near-by source in the field or else in the laboratory. If in the laboratory, precautions were taken against exposing the contents of the bottles to contamination. The tops were loosened and lifted on one side only, and then just enough to permit the entrance of a sterile pipette, filled with sterile water. By working expeditiously no more danger of contamination from the air resulted than in making trans- fers from one culture medium to another. The favorite places for hibernation on the part of the chinch bugs, apparently, were the stools of the prairie grass, Androfogon sco- parius. The grass was uprooted and some of the bugs placed in bottles by the use of sterile lifters. Several bottles of bugs, together with a portion of the surrounding earth, were collected in at least one locality in each county visited. It was desired to ascertain if a spontaneous outbreak of the fungus could be obtained among the incarcerated bugs. Since, under the natural conditions to which the bugs were subjected in the bottles, 18 THE WHITE-FUNGUS DISEASE IN KANSAS. there was a possibility that the proper conditions might not be secured in some of them for the fungus to develop, the uncer- tainty was eliminated by having a number of bottles from each locality. Sporotrichum appeared in most of the bottles (see PL I), though its occurrence in but one of a series was sufficient to establish the certainty of its presence in the locality from which the collection had come. In some of the bottles no Sporotrichum developed. This was generally due to an excess of moisture which caused bugs to die before the Sporotrichum had time to make its presence manifest. The chinch bugs in the bottles generally showed remarkable powers of endurance, as they were without food yet in warm sur- roundings. Some were found still crawling more than two months after collection and long after observations were taken. Some con- tinued to live for this length of time with the Sporotrichum present and projecting conspicuously from dead bugs (see PL II) over which they frequently crawled. Thirty-two counties in the infested area of Kansas were definitely shown to contain the white-fungus disease among the chinch bugs before egress from their winter quarters, during the latter part of March. The first package of diseased bugs was sent out April 7 by the Kan- sas State Agricultural College at Manhattan. Five days later the University began its distribution of diseased bugs. It is therefore evident that Sporotrichum was present naturally in the localities examined and only needed the proper climatic conditions to break out spontaneously in the fields. Natural Presence or Sporotrichum in Wheat Fields and Corn- fields DURING THE SpRING AND SuMMER OF 1910. Spontaneous outbreaks. — The chinch bugs left their winter quar- ters the last week in March, but owing to the dryness and coolness of April, no diseased bugs were found in the fields until late in the month. In the meantime the collecting of bugs and testing for the presence of the fungus continued. Later, when fungus-covered bugs were present in the fields, they were considered as direct evidence of its natural distribution, provided artificial distribution had not been resorted to. Observations on the jDresence of Sporotrichum among chinch bugs in grain fields occupied the months of April, May, and June. During this time 27 additional counties were shown to contain the fungus. Summing up the work on the natural distribution of the fungus disease, it was found that 59 counties, which include most of the infested area of Kansas, showed evidence of its presence. Six coun- ties, four of which were on the western edge of chinch-bug distribu- NATUEAL PRESENCE IN" FIELDS. 19 tion, where excessive drought or else scarcity of bugs constituted the conditions met with, failed to show presence of Sporotrichum. Two counties, on the northeastern border, because of great scarcity of bugs, also failed to show signs of fungus. A few counties situated amono- others in which Sporotrichum was observed probably contained it, but, as they were not visited, no direct evidence was obtained. Granting its absence in such localities in 1910, however, it would be but a short time, owing to migration of the chinch bugs, before 20 THE WHITE-FUNGUS DISEASE IN KANSAS. spores from the adjacent counties would be carried over into every field where they might alight. As will later be shown, Sporotrichum is not dependent on chinch bugs for hosts, but may live on other insects. There is hardly any question as to the presence of the fungus in the soil generally. Maintenance of Sporotrichum in the soil. — From the ease with which Sporotrichum is cultivated in the laboratory at room tem- perature with dead organic substances as culture media, it is possible that it projjagates itself, at times, saprophytically in the soil. It is not dependent, however, either on dead organic matter or on living chinch bugs, but may live as a parasite on other insects, some of which are present in Kansas as permanent fauna. Various writers from widely separated localities have reported Sporotrichum on insects other than chinch bugs. While making no attempt to search for the fungus on other than chinch bugs, the writers noticed insects from time to time displaying the characteristic Sporotrichum growth. A list of them is given below. Insects upon which Sporotrichum has been Found. Three common snout beetles, Trichoharis texana, G onotrachelus erinaceus^ and Anthonomus fulvus (PI. Ill, figs. 1, 2, and 3) ; a com- mon flea-beetle, Disonycha triangularis (PL III, fig. 4;) a very com- mon lady-beetle, Hippodamia convergens (PL III, fig. 5) ; a minute beetle of the genus Olihrus (PL III, fig. 6) ; and three true bugs belonging to the same order (Hemiptera) as the chinch bug, one a rather rare insect, belonging to the family Phymatidae, the species un- determined, and the other two common forms, Microtoma carhonaria and Coriscus ferus (PL IV, figs. 1, 2, and 3), and two unidentified larvae (PL IV, figs. 5 and 6), and many common pentatomids. Natural Distribution of Sporotrichum in the Soil and its Kela- TiON TO Artificial Infection. The general distribution of Sporotrichum naturally in the soil might affect the artificial use of the fungus in one of two ways — ^by rendering it unnecessary, or by making it more effective. In the former instance a spontaneous outbreak would occur, which, if con- ditions were right, would be of such magnitude that, whatever man might do in the way of artificially distributing fungus spores, noth- ing appreciable would be added to the results ; or, given unfavorable conditions with a slight spontaneous outbreak, or none at all, artificial infection would not measurably spread the disease. In the second instance when there is already a spontaneous outbreak of considerable size, artificial infection might increase this to an epidemic that would end in a high percentage of mortality among the bugs. Other Bui. 107, Bureau of Entomology, U. S. Dept. of Agriculture. Plate III. Various Insects Killed by Fungus Diseases. No. 2 is Isaria sp., the OTHERS SPOROTRICHUM. (ORIGINAL.) Fig. l.— Tiichobaris texana. Fig. 2. — Conotrachelus erinaceus. Fig. 3. — Anthnnomus fulvus. Pig. 4. — Disonijcha triangularis. Fig. 5. — Hippodamia convergens. Fig. 6.—Olibnos sp. Bui, 107, Bureau of Entomology, U. S. Dept. of Agriculture. Plate IV. Various Insects Killed by the Chinch-Bug fungus, Sporotrichum globuliferum. (original.) Fig. 1.- Fig. 2.- -MacrDcrpliahis sp. -Micrutotiia atrata. Figs. and 0.- Fig. 2.—Co)-iscusferiis. Fig. 4. — C'urisniK ferun, iivniph. -Unidentified larv?e. INFECTION EXPERIMENTS IN LABORATORY. 21 fields not artifically treated would then show merely a spontaneous outbreak with a lower percentage of mortality. The settlement of these problems was merely a matter of experiment under conditions that would cover possibilities mentioned above. As soon as spring opened and weather permitted, field investigations began; the pur- pose being to ascertain whether artificial treatment of a field infested by chinch bugs would prove profitable. One phase of the matter as described earlier in this paper had already been settled; the Sporotrichum disease was widespread naturally over the infested sec- tion of the State. It remained to be shown, first, whether sowing fungus spores in an already infested field would increase the epidemic, and, second, in a field showing but little evidence of Sporotrichum whether such a treatment would start an epidemic, otherwise im- probable. Artificial. Infection Experiments with Sporotrichum in the Laboratory. Preparatory to the field work it was found necessary to experiment with the fungus in the laboratory in order to determine the best method of propagation and the effect of the artificially grown cultures on chinch bugs. Quite definite results had already been obtained by Stevens, Barber, and Forbes, and advantage was taken of their conclusions, but at the same time it was thought best to experiment anew and adopt the methods best adapted to the experiments in hand. Sporotrichum was first isolated from transfers made into nutrient agar from a chinch bug dead of the disease. Once obtained pure, there was no difficulty in propagating it on artificial media. For field infection large quantities were needed, so that infection boxes which were designated for infecting bugs for distribution to farmers proved inadequate. The 10 c. m. petri dish used in bacteriological investigation was selected as the vessel in which to place the nutrient medium for growing the Sporotrichum. The fun- gus will grow on ordinary beef broth agar, but this was not found so useful as a combination of potato extract and corn meal. Virulence of artificial cultures. — It was realized early in the in- vestigation that the value of any work along lines of field infection depended upon a knowledge of the virulence of artificial cultures, since these were to be employed to a large extent. It was found that so much more fungus could be produced artificially with such cer- tainty that diseased bugs, while used, were not depended on for the major part of the work. To test the virulence of the fungus, experi- ments were conducted at various times by artificially infecting chinch bugs with culture fungus (that grown on the potato-cornmeal medium) and then comparing results with others not so infected or infected by the use of diseased bugs. 22 THE WHITE-FUNGUS DISEASE IN KANSAS. Experiment 1. — This experiment was started April 29, the bugs being collected at Colony, a locality which showed an extraordinarily small amount of Sporotrichum in the soil when compared with other localities (except Garnett, in the same county). By selecting bugs from Colony it was hoped to avoid, as far as possible, the presence of spores on the bugs or in the soil before the experiment began. The insects were collected in five sterile bottles, with an approximately equal quantity in each. One bottle was infected with spores from an artificially grown culture. The other four bottles were not opened after they were sealed in the field. By May 13 three diseased bugs were noted in the infected bottle. Four days later all the bugs in the bottle were dead and about half of them were covered with a visible and typical growth of Sporotrichum. The bugs were dead in the four check bottles, but no fungus developed. Experiment 2. — This experiment was designed to reach the same as the previous one, but by a different method. It began May 7. Six screw-capped bottles, each containing 100 grams of earth, were sterilized in an autoclave. Bugs direct from the field and not arti- ficially infected were placed in three of them. To the other three bottles were added bugs, in approximately equal numbers, which had been allowed to crawl for two hours over a moist Sporotrichum culture. Final observations were taken 10 days later. In the uninfected bottles no fungus developed. Two of the other three contained two and eight diseased bugs, respectively. Xo fungus appeared on the third. The short period of 10 days duration to an extent eliminated deaths by Sporotrichum resulting from extreme weakness due to pro- longed incarceration and starvation. Experiment 3. — ^This experiment was designed to compare the rela- tive effectiveness of fungus grown on a culture medium and that arising naturally on chinch bugs. Thirty sorew-capped bottles were prepared with 100 grams of soil in each bottle, then the whole was sterilized in the autoclave. About 18 chinch bugs were placed in each bottle. A sterile pair of forceps was used to transfer the bugs, and unsterilized field earth was avoided as far as possible. Bottles 1 to 10 were checks. No. 10 having no infected material added. Bot- tle 11 contained bugs which had been shaken up in a small box with three fungus-covered bugs which were finally added to the bottle before it was sealed. Bottle 12 was prepared in the same manner. Bottles 13-17 contained bugs that had been shaken up with a lot of crushed diseased bugs. Bottles 18-20 contained bugs that had been shaken up with soil which had previously been made infectious by rubbing up diseased bugs in it. Bottles 21-30 contained bugs that had been allowed to crawl over a mass of Sporotrichum grown on culture medium. INFECTION" EXPERIMENTS IN LABOEATOEY. 23 All bugs were collected at Cherryvale, a locality that showed an abundance of Sporotrichnm in the soil; hence the positive results in the check bottles. The experiment began May 7, and by May 24 all the bugs iii all the bottles were dead. The results are tabulated below : BOTTLES 1 TO 10. 1 2 3 4 5 6 7 8 9 10 Date. Number of diseased bugs. ^ay 10 ^ay 13 1 1 1 j^ay 16 1 1 May 24" ! 1 2 1 1 2 1 Total number of diseased bugs, 13. BOTTLES 11 TO 20. Bottle No 11 12 13 14 15 16 17 18 19 20 Dat«. Number of diseased bugs. 2 1 1 1 1 1 1 3 1 "2 2 1 May 13 1 2 1 1 1 6 2 2 4 2 2 May 16 - -.- 4 May 24I 1 1 4 Total number of diseased bugs, 53. BOTTLES 21 TO 30. Bottle No 21 22 23 24 25 26 27 28 29 30 Number of diseased bugs. May 10 1 2 3 1 2 10 1 1 May 16 . 1 May 24,. 17 6 11 1 3 15 6 15 9 Total number of diseased bugs, 105. It is possible that bottles 21-30 had more spores attached to them than those in the other bottles, but that the spores possessed viru- lence is shown by the results in mortality. Experiment Jf, — This experiment was begun May 17. Forty-eight screw-capped bottles, each containing an equal amount of earth, were sterilized in an autoclave. Twelve adult chinch bugs were then •placed in each bottle. Twenty-four bottles were kept as checks (uninoculated) , and 24 were inoculated as follows: Thirteen bottles by allowing bugs to crawl over spores from a culture and 11 bottles by scattering similar spores into the bottles with a camel's-hair brush. The brush was rolled in a mass of the spores in a petri-dish culture and then struck sharply against the lip of the bottle. A cloud 24 THE WHITE-FUNGUS DISEASE IN KANSAS, of spores was thereby dislodged, which so filled the bottle that every chinch bug must have come into contact with them. On May 22 the results were as follows: Bottle No 1 2 3 4 5 6 7 8 9 10 11 12 13 Number of diseased bugs. Inoculated 4 8 10 1 12 12 1 11 12 10 11 1 11 S 9 2 1 ^?, Checks 1 Bottle No 14 15 16 17 18 19 20 21 22 23 24 Total. Number of diseased bugs. Inoculated • - Checks - • 7 12 1 10 6 5 9 8 1 10 11 2 ,0 1 9 227 12 Expei^ment 5. — The last of the series on virulence was begun on July 14, this late date being selected for the reason that the cultures then in the laboratory had been running saprophytically since the original isolation of the fungus in January, 1910, and there was a question whether such prolonged cultivation on artificial media had had the effect of lowering the virulence and hence weakening the power of the fungus in attacking chinch bugs. As the latter part of July was the time in which the field experi- ments were terminated, it was pertinent to know whether the fungus used in field inoculation during June and July had retained the parasitic nature evidenced by the earlier experiments of this series on virulence. Experiment 5 was arranged to compare inoculations with artificially grown fungus with natural infection. Natural infec- tion was presupposed, since there was no field found where Sporo- trichum did not exist naturally to some, even though to small, extent. The method of procedure differed but slightly from that in experi- ment 4. Forty screw-capped bottles were partially filled with 100 grams each of moistened and thoroughly mixed earth. They were then sterilized with 15 pounds pressure in an autoclave. Ten adult chinch bugs were placed in each bottle. Twenty bottles were infected by the camel's-hair brush method described in experiment 4. The other 20 were checks. The bottles were watched, and it was soon noticed that Sporo- trichum was appearing among the treated bugs at a much faster rate than among the untreated. The disease in the checks was undoubt- edly introduced with the bugs and was present on them when they were collected from the field. But the same amount of natural fungus approximately would be present in the bugs in the inoculated bottles, so that final results would be but little affected. INFECTION EXPEEIMENTS IN LABORATOEY. 25 The bottles were opened July 23 and the number of Sporotrichum- covered buss ascertained. CHECK BOTTLES. Bottle No 1 2 3 4 5 6 7 8 9 10 11 "NTiiTnhftr nf HisfinsfiH hng?eat~- ~ ^ ~ ~I~Zr ^3 32 'vIC^ X — -- -- .n — - O -- ■ — -- o — — D Fig. 4. — Diagram illustrating the oiled-ridge type of barrier — b, barrier ; p, postholes. A partial barrier between the wheat and corn would extend from a to b. (Original.) upon the ridge and form a bridge over the repellent stream for the chinch bugs to cross. Eternal vigilance will be the price of success. The crude oil-straw harrier. — An experiment was tried in which straw dipped in crude oil was used as the repellent part of the bar- rier. It gave promise of success, especially when small fields were to be protected. To erect a barrier of this kind the farmer would need, besides the straw and crude oil, a tube or barrel mounted on a sled or wagon, a pitchfork, and a posthole digger. The oil is placed in the barrel or tub and the straw dipped into it and laid in a long- windrow about a foot wide and from 4 to 6 inches high. This is the barrier. Postholes are dug on the wheat-field side of the barrier about 75 feet apart and so that the straw somewhat overhangs the edges of the postholes. Loose soil or air-slaked lime on the sides of the openings facilitates the fall of the bugs into the postholes. The advantages of the oiled-straw barrier are its cheapness and the fact that it is not easily affected by weather conditions. Heavy REMEDIAL MEASURES AND CONCLUSION'S. 51 rains tend to wash the oil off, but it can be renewed easily with a garden sprinkler. Under ordinary conditions the original oiling will j^robably suffice. The volatile products of the oil keep the bugs from crawling be- neath the barrier, and the difficulty of crawling along straws lying in every direction and coated with the offensive-smelling oil discour- ages the bugs from their attempts to crawl over. It is to be regretted that the oiled-straw barrier was not thought of soon enough to make a test of its practicability in protecting an entire field. A small patch of corn in a field into which the invasion of the bugs had already begun was surrounded by a barrier of this kind in order to ascertain its effectiveness. A few bugs were already in the corn inclosed by the barrier, but these were removed by hand and thrown outside. Any bugs that were subsequently found in the corn, therefore, presumably had crossed the barrier. The experi- mental corn patch lay in the direct line of march of the principal mass of migrating bugs. The barrier was prepared June 23, 1910. During the next five days no fresh oil was applied, and a torrential rain washed out some of the oil with which the straw was originally saturated, leaving the upper straw odorless and reducing the oil beneath, so that the odor was faint. As a result, a few chinch bugs were found crossing the bar- rier on the uppermost straws. None was passing underneath. A second application of oil was made with a garden sprinkler. Had it been made immediately after the rain, probably no bugs would have crossed the barrier. No further application of oil was made. The field was inspected July 6. Only a trace of rain had fallen in the meantime, and the barrier had retained the odor of the oil, and consequently retained its effectiveness throughout the remaining pe- riod of the attack. The bugs within the inclosure were so few in number that no ma- terial damage was done to the corn, and consequently the stalks had made a nearly normal growth and presented a striking contrast to the corn outside of the inclosure, which lay withered on the ground. No postholes had been dug, so that the insects encountered the bar- rier, passed around it, and then straight on into the corn beyond. A few, however, turned into the corn back of, and protected in part by, the inclosed patch. But as they did not damage it much, it grew and appeared nearly as vigorous as the corn within the barrier. By July 28 the chinch bugs had scattered, but they had left a trail of destruction in their path, all the corn being killed except the small patch protected by the oil-straw barrier and the corn immediately back of it and an occasional stalk here and there which had escaped serious injury. (See PI. V, fig. 1.) A harrier inclosing a field versus a harrier along one side only. — Barriers are usually erected only between the field from which the 52 THE WHITE-FUNGUS DISEASE IN KANSAS. bugs are about to migrate and the field to be protected. Such bar- riers are of value in preventing the injury caused by the massing of the bugs in the proximal side of the field into which the bugs are endeavoring to migrate, and by permitting destruction to a vast number of the invading host, but it should be remembered that when a field of grain that is infested with chinch bugs is harvested the bugs leave in all directions. If the barrier is erected along one side of the field only, the bugs which escape from the other sides of the field manage to live on grasses and other vegetation, which usually can be readilj' found, until they get their wings, when they take wing and finally get into the corn. They not only injure it, but raise another brood, the adults of which pass the winter and come out in the spring to continue their ravages. Just before harvest practically all the chinch bugs in any community will be found in the grain fields, and if each one of the grain fields in the community were surrounded by an effective bar- rier such a large percentage of the bugs could be destroyed that the community would be rid of bugs in injurious numbers. If this could be done throughout the entire infested area there is little doubt but that the bugs could be successfully controlled and thousands of dol- lars' worth of damage prevented. However, a barrier along one side of a field is worth while and is to be recommended when for any reason it is not possible to erect it on all sides of the field. Spraying. — It may happen that because of delay in getting an effective barrier up, the bugs get into the cornfield and mass them- selves on the first rows. When this occurs the spray pump should be brought into use, and the bugs killed with kerosene emulsion or else with crude oil. Kerosene emulsion. — The emulsion is made as follows: Dissolve 1 pound of laundry soap in 1 gallon of boiling rain water, then while hot add 2 gallons of kerosene, or coal oil, and stir vigorously with a stick for 10 minutes. The solution will soon take on a creamy appearance, but the stirring should be kept up for the full time. After the stirring is complete, from 27 to 47 gallons of rain water may be added according to the strength of the solution desired. By adding 47 gallons a 4 per cent solution is obtained, and Prof. Forbes and others have found this solution strong enough to kill most of the bugs and not injure the corn ; but in our experiments this season we found that a 4 per cent solution did not kill the bugs to our satisfac- tion, and that the stronger solution, made by adding only 27 gallons of water, killed the bugs almost instantly and did not injure the com to any extent when care was taken not to let the spray run down the inner circle of leaves at the crown. The important result to be obtained is the destruction of the bugs. As to whether the few rows of corn sprayed are injured or not, that is a minor consideration. If the bugs can be killed by the weaker solution and the corn saved, well Bui. 107, Bureau of Entomology, U, S. Dept. of Agriculture. Plate V. Fig. 1.— Patch of Corn Protected by the Oiled-straw Barrier, and Showing THE Destruction of the Corn Outside of the Barrier. (Original.) Fig. 2.— Cornfield Showing Corn that was Treated with Crude Oil. The Large Stalks in the Lower Right Foreground are in the Row Treated. (Original.) REMEDIAL MEASURES AND CONCLUSIONS. 53 and good, but if the farmer finds that the bugs on the stalks sprayed are alive when examined an hour after being sprayed, he should use a stronger solution even if it does injure the corn. Crude oil. — During the summer campaign an experiment was per- formed in Mr. Metcalf's field at Cherryvale, in which crude oil was applied directly to the cornstalks when they were badly infested with bugs. It was at first supposed that the oil might kill the corn ; but it was found that, when applied to the lower portion of the stalks and the lower leaves, little or no harm resulted. A field of corn lying north of a wheat field was exposed to a mi- gration of chinch bugs. No barrier was used and consequently the bugs migrated into the corn. It was noticed that the great majority of the bugs were located on the stalks and lower leaves. A badly infested row was used for experiment and a checkrow, as yet unin- fested, was treated in the same way. A bucket of crude oil was taken into the field and the oil dashed on the corn and the bugs with a bunch of coarse weeds gathered along the roadside. At the first stroke many of the bugs dropped to the ground, and the weeds were used to dash oil on them. Each hill in the row was liberally treated with oil and also the ground about the hill wherever the bugs were seen. The bugs were killed instantly and the oil protected the stalks from further attack. The two treated rows were watched for injury to the corn due to the oil. A personal inspection a month later showed no harm done, and a letter from the owner in the autumn declared that the rows matured corn in normal manner. The only precaution taken in applying the oil was to prevent the oil from get- ting into the crown of the young leaves. This method has not been tested thoroughly enough to warrant us in giving it our unqualified reconmiendation, but so far it has proved very destructive to the bugs and has not resulted in any material injury to the corn. The use of sprays or crude oil should not take the place of barriers, but should be used as a supplementary measure only. (See PI. V,fig. 2.) The expense of making this campaign is very slight compared with the loss which the chinch bugs will occasion if not molested. The reasons mostly given by the farmers for not taking up this fight against the bugs is that they do not have time to bother with it. But if it is profitable to employ help to raise a crop it would seem that it ought to be profitable to put forth some little effort to save it after it is raised. How to secure concerted action. — This whole subject needs to be agitated among the farmers. Township meetings should be called, the question discussed, and an organization formed for concerted action. At the first meeting called perhaps only a small number of farmers, the most progressive, will attend. With the organization formed, the agitation should be taken up by everyone interested. A time should be set for burning in the fall and efforts made to get 54 THE WHITE-FUNGUS DISEASE IN KANSAS. everyone to burn at that time. In the matter of summer treatment, the coal tar or crude oil could be ordered for a whole township at one time, resulting in a saving. Active preparation for the fight made by a large number before the time for the fight to begin will have a wholesome effect upon those who are lukewarm in their attitude toward it. SUMMARY. 1. Organize by townships or school districts and counties. 2. Set a time for burning in the fall. 3. It it is not practicable to burn off all lands where there are weeds and rubbish, burn at least all lands where there are tufts of grass, and especially if they are in close proximity to cornfields. 4. Before wheat harvest secure a good spray pmnp and at least a barrel of coal tar or No. 18 residuum asphaltum for every 80 rods of barrier to be erected about wheat fields, or two barrels of crude oil for the same amount of barrier. 5. If the weather is dry at harvest time, erect a dust barrier around the infested field. Plow deep so as to cover completely all the stubble and trash, harrow and drag, then throw out a furrow near to the outside border, and start the log as soon as the bugs begin to migrate. 6. If rain should come, fix up a tar or crude oil barrier around the infested field. 7. Spray bugs that escape to the corn with kerosene emulsion or apply crude oil. 8. Keep up the fight as long as the bugs keep coming from the field. Bibliography. Note. — The attention of those who are specially interested in the subject of insect dis- eases is called to Dr. S. A. Forbes's excellent bibliographies : Economic Bibliography of the Chinch Bug, published as an appendix to the Sixteenth Report of the State Entomol- ogist of Illinois, and as an Analytical List of American Articles (on Diseases of Insects) Consulted, 1824-1894, published in the Nineteenth Report of the State Entomologist of Illinois, 1896. 1. Shimee, Henky. — Notes on Micropus (Lygceiis) leucopterus Say ("The chinch bug"), with an account of the great epidemic disease of 1865 among insects. (Proc. Acad. Nat. Sci. Phila., May, 1867, v. 19, pp. 75-80; and Trans. Northern 111. Hort. Soc, 1867-68, pp. 97-101.) 2. Shimee, Henky. — Additional notes on the chinch bug. (Proc. Acad. Nat. Sci. Phila., 1867, v. 19, p. 234.) 3. Shimee, Heney. — Nature's method of controlling insects. (Trans. Nor. 111. Hort. Soc. 1867-68, p. 96.) 4. Walsh and Riley. — The chinch bug. {Micropus leucoptervs, Say.) (Amer. Ent, May and June, 1869, v. 1. p. 177.) 5. Shimee, Henky. — Entomological notes. (Trans. 111. State Hort. Soc, 1869, V. 3, n. s., pp. 275-281.) 6. Riley, C. V.— The chmch bug. (Second Ann. Rept. State Ent. Mo., pp. 24-25, 1870.) 7. Le Baeon, Wm.— The chinch bug. (Third Rept. State Ent. 111., 1871, pp. 142-156. Also Fifth Ajin. Rept. Board of Trustees 111. Industrial Univ., 1871-72, pp. 193-200.) BIBLIOGRAPHY. 55 8. Thomas, Cyrus.— The chinch bug. (Bui. 5, U. S. Ent. Comm., 1879.) 9. FoEBES, S. A.— The chinch bug in 1882. Field notes. (Illinois crop reports. Consolidation of reports returned to the Department of Agriculture Aug. 1, 1882. Circ. 92, p. 77 ; Western Rural, 1882, Farmers' Review, Oct. 19, 1882.) 10. Forbes, S. A. — Bacterium a parasite of the chinch bug. (Amer. Nat., Oct., 1882, V. 16, p. 224.) 11. PoPENOE, E. A. — The chinch bug and the season. (Prairie Farmer, Nov. 25, 1882.) 12. Forbes, S. A. — Another chinch bug parasite. (Prairie Farmer, Dec. 9, 1SS2.) 13. Forbes, S. A.— Studies on the chinch bug. 1. (Twelfth Rept. State Ent. 111., 1882, pp. 32-63. Brief summary of discussion in Bui. 111. State Lab. Nat. Hist., V. 2, p. 258.) 14. FoBBES, S. A. — Lecture on insects affecting com, pp. 17-20. (Read before a Farmers' Institute at the State Indus. Univ., Champaign, 111., Jan. 29, 1883, and issued in pamphlet form the same year. Review in Advanced Farmer, July, 1883.) 15. BuRRiLL, T. J. — New species of micrococcus (bacteria). (Amer. Nat., March, 1883, v. 17, p. 319.) 16. Forbes, S. A. — Memoranda with regard to the contagious diseases of insects and the possibility of using the virus of the same for economic purposes. (Can. Ent, Sept., 1883, and Amer. Nat., Nov., 1883, v. 17, p. 1170) 17. Forbes, S. A. — Entomological notes of the season. (111. Crop Rept. No. 106, Dec, 1883, p. 178.) 18. Packard, A. S. — The chinch bug. (Guide to the study of insects.) 19. Weed, C. M. — Rise and fall of the chinch bug. (Prairie Farmer, Oct. 31, 1885.) 20. Forbes, S. A. — Chinch bugs in Illinois. (Prairie Farmer, July 31, 1886.) 21. Forbes, S. A. — The chinch bug in Illinois. (Circular from Office State Ent. 111., Champaign, 111,, Sept. 10, 1886, p. 8.) 22. Forbes, S. A. — Present conditions and prospects of chinch bugs in Illinois. (Bui. Office State Ent. 111. No. 2, 1887; Fifteenth Rept. State Ent. 111.) 23. Howard, L. O.— The chinch bug. (Bui. 17, o. s., Div. Ent, U. S. Dept Agr., p. 48; Rept. U. S. Comm. Agr., 1887, pp. 51-88.) 24. Bruner, Lawrence. — Report on the season's observations in Nebraska. Chinch bug. (Rept. U. S. Comm. Agr., 1887, p. 165.) 25. Forbes, S. A. — On present state of our knowledge concerning contagious in- sect diseases. (Psyche, v, 5, Jan.-Feb., 1888, p. 3.) 26. Gillette, C. P. — ^A new chinch-bug enemy. (Prairie Farmer, Aug. 11, 1888, V. 60, p. 518.) 27. Gillette, C. P. — Chinch-bug diseases. (Bui. 3, Iowa Agr. Exp. Sta., Nov., 1888, p. 57.) 28. Forbes, S. A. — Epidemic diseases of the chinch bug in Illinois. (Ins. Life, V. 1, No. 4, Oct., 1888, p. 113.) 29. Patrick, I. A. — The new chinch-bug enemy. (Prairie Farmer, Aug. 25, 1888.) 30. Forbes, S. A.— Chinch bugs. (Prairie Farmer, Oct. 6, 1888,- v. 60. p. 650; Farmers' Review, Oct 10, 1888, v. 19, p. 642.) 31. Forbes, S. A. — Chinch-bug diseases. (Farmers' Review, Oct. 31, 1888, v. 19, p. 692.) 32. Lugger, Otto. — Fungi which kill insects. (Univ. Minn., Coll. of Agr. Bui. 4, p. 37; Abstracts in Farmers' Review, Nov. 14, 1888, p. 721.) 33. Lugger, Otto. — Notes on the chinch bug in Minnesota. (Ins. Life, v. 1, No. 4, Oct., 1888, p. 113.) 56 THE WHITE-FUNGUS DISEASE IN KANSAS. 34. Forbes, S. A. — Notes on chinch-bug diseases. (Psyche, v. 5, Sept.-Oct., 1888, p. 110.) 35. Snow, F. H. — The chinch-bug, BUssus leucopterm. Say. (Sixth Bien. Rept. Kans. State Board Agr., 1887-88, pp. 205, 208; Proc. 18th Annual Meeting Kans. State Bd. Agr., p. 78.) 36. Forbes, S. A. — Studies on chinch bug, II. (Sixteenth Rept. State. Ent. 111. 1887-88, pp. 45-59.) 37. Snow, F. H. — Experiments for the artificial dissemination of a contagious disease among chinch bugs. (Proc. 19th Meeting State Bd. Agr., pp. 142- 144; Trans. Kans. Acad. Sci., v. 12, pp. 34-37.) 38. Webster, F. M.— The chinch bug. (Bui. No. 22, old series, Div. Ent., U. S. Dept. Agr., 1890, pp. 60-63.) 39. Snow, F. H. — Chinch bugs. Experiments in 1890 for their destruction by the artificial introduction of contagious diseases. (Seventh Bien. Rept. Kans. Bd. Agr., 1888-90, pp. 14.S-188.) (Twenty-first Ann. Rept. Ent. Soc. Ont, 1890, pp. 93-97.) 40. Riley, C. V. — The chinch-bug Entomopthora. (Ins. Life, v. 2, No. 5, Nov., 1889, p. 126.) 41. Forbes, S. A. — The chinch-bug probabilities. (Belleville [Illinois] Advo- cate, Mar. 15, 1889.) 42. Riley, C. V.— The work of field agents. (Rept. U. S. Sec. Agr., pp. 339-360.) 43. Forbes, S. A. — Economic bibliography of the chinch bug. (Appendix to Six- teenth Rept. State Ent., 111., 1890, pp. 1-122.) 44. Osborn, Herbert. — Entomology. (The Orange Judd Farmer, Mar. 8, 1890, p. 158.) 45. Osborn, Herbert. — On the use of contagious diseases in contending with injurious insects. (Ins. Life, v. 3, No. 4, Nov., 1890, pp. 141-145.) 46. Snow, F. H. — Experiments for the destruction of chinch bugs in the field by the artificial introduction of contagious diseases. (Ins. Life, v. 3, No. 6, March, 1891, pp. 279-285.) 47. Snow, F. H. — The chinch-bug disease and other notes. (Ins, Life, v. 5, Nos. 1 and 2, Oct., 1891, pp. 69-72.) 48. Osborn, Herbert. — Fungus infection of chinch bugs. (The Orange Judd Farmer, Aug. 8, 1891, p. 85.) 49. Osborn, Herbert. — The chinch-bug cholera, etc. (The Orange Judd Farmer, Oct. 17, 1891. p. 245.) 50. Cook, A. J. — On carrying chinch-bug disease over winter. (Ins. Life, V. 3, No. 6, March, 1891, p. 285.) 51. Fletcher, James. — Chinch-bug disease. (Ins. Life, v. 3, No. 6, March, 1891. p. 285.) 52. Snow, F. H. — Destruction of chinch bugs. (Scient. Amer., May, 1891, p. 311.) 53. Forbes, S. A.— General record for 1889 and 1890. ( Seventeenth Rept. State Ent. 111., p. 9.) 54. Forbes, S. A. — Notes on the diseases of the chinch bug. ( Seventeenth Rept. State Ent. 111., p. 74.) 55. Forbes, S. A. — On the bacterial insect disease. (North Amer. Practitioner, 1891, p. 401; Amer. Monthly Micro. Journ., 1891, p. 246.) 56. PoPENOE, E. A. — The chinch-bug disease again. (Manhattan Nationalist, Feb. 13, 1891.) 57. Riley, C. V. — The outlook for applied entomology. (Ins. Life, v. 3. No. 5, Jan., 1891, p. 181.) 58. Riley, C. V. — A discouraging fact in Prof. Snow's experiments. (Ins. Life, V. 3, No. 6, March, 1891. p. 279.) BIBLIOGKAPHY. 57 59. Riley, C. V. — Microorganisms as insecticides. (Scient. Amer. Supp., Oct. 31, 1891, V. 32, p. 13206.) 60. Webstkr, F. M. — Means suggested for the outdoor continuance of tlie Ento- mopttiora from year to year. (Ins. Life, v. 3, No. 6, Marcli, 1891, p. 285.) 61. Snow, F. H. — Tlie cliinch-bug disease and other notes, (Ins. Life, v. 4, Oct., 1891, pp. 69-72.) 62. Snow, F. H. — Experiments for the destruction of chinch bugs by infection. (Psyche, v. 6, No. 191. March, 1892, pp. 225-233.) 63. Forbes, S. A. — Bacteria normal to the digestive organs of Hemiptera. (Bui. III. State Lab. Nat. Hist, v. 4, pp. 1-7.) 64. FOKBES, S. A.— The chinch bug in Illinois, 1891, 1892. (Bui. 111. Agr. Exp. Sta., No. 19, 1892, p. 48.) 65. Forbes, S. A. — The work of the year on contagious diseases of insects. (Ins. Life, V. 5, No. 1. Sept. 1892, p. 68.) 66. Snow, F. H. — Contagious diseases of the chinch bug. (First Ann. Kept. Dir. Kans. Univ. Exp. Sta., 1891.) 67. Snow, F. H. — Contagious diseases of the chinch bug. (Second Ann. Rept. Dir. Kans. Univ. Exp. Sta., 1892.) 68. Webster, F. M. — Insect foes of American cereals, with measures for their prevention or destruction. (Ins. Life, v. 6, No, 2, Dec., 1893. p. 146; Bui. Ohio Agr. Exp. Sta., No. 51, p. 130.) 69. Snow, F. H. — Contagious diseases of the chinch bug. (Third Ann. Rept. Kans. Univ. Exp. Sta., 1893.) 70. Forbes, S. A.— General record for 1891-1892. (Enghteenth Rept. State Eut. 111., p. 10.) 71. Beuner, Lawrence, and Barber, H. G. — Experiments with infectious dis- eases for combating the chinch bug. (Bui. Neb. Agr. Exp. Sta., May, 1894, No. 34, pp. 143-161.) 72. Snow, F. H. — Work in economic entomology in the University of Kansas for the season of 1894. (Ins. Life, v. 7, Oct., 1894, pp. 140-144.) 73. Bbuner, Lawrence. — Reports on injurious insects in Nebraska and adjoin- ing districts. (Bui. 32, Div. Ent., U. S. Dept. Agr., 1894, pp. 9-21.) 74. Forbes, S. A.— -The chinch bug in Illinois, 1894. (Press Bui. 16. June 9, 1894, 111. Agr. Exp. Sta.) 75. Forbes, S. A.— Chinch-bug experiments. (Special Bui. HI. Agr. Exp, Sta,, June 30, 1894.) 76. Forbes, S. A. — How to fight chinch bugs. (Prairie Farmer, Aug. 4, 1894, V. 66, p. 2.) 77. Forbes. S. A — The chinch bug in 1894. Contagious disease experiments. (Bui. State Ent, 111., No. 5.) 78. Webster, F, M, — Vegetal parasitism among insects, (Journ. Columbus Hort, Soc, April, 1894,) 79. Lugger, Otto.— The chinch bug. (Bui. 87, Minn, Agr. Exp. Sta., Dec, 1894, pp. 153-782.) 80. Forbes, S. A, — Recent progress in horticultural entomology, (Trans, 111. State Hort. Soc, 1895, pp. 137-148.) 81. OsBORN, Herbert, — Observations of insects, season of 1894, (Bui. 27, Iowa Agr. Exp. Sta., 1895, pp. 135-149.) 82. Lugger, Otto. — Insects injurious in 1895. (Bui. 43, Minn. Agr. Exp. Sta., Jan., 1896, pp. 99-251.) 83. Pettit, R. H. — Studies in artificial cultures of entomogenous fungi. (Bui. 97, Cornell Univ. Agr. Exp. Sta., July, 1895, pp. 339-.37S.) 84. Forbes, S. A. — Experiments with the muscardine disease of the chinch bug, etc (Bui. 38, 111. Agr. Exp. Sta., March, 1895, pp. 25-86.) 58 THE WHITE-FUNGUS DISEASE IN KANSAS. 85. Snow, F. H. — Contagious diseases of the chinch bug. (Fourth Ann. Rep. Dir. Kans. Univ. Exp. Sta., 1894.) 86. Snow, F. H. — Contagious diseases of the chinch bug. (Fifth Ann. Rep. Dir. Kans. Univ. Exp. Sta.. 1895.) 87. Snow, F. H. — Contagious diseases of the chinch bug. (Sixth Ann. Hep. Dir. Kans. Univ. Exp. Sta., 1896.) 88. Stedman, J. M. — Chinch-bug infection. (Cir. of Information, 2, Mo. Agr. Exp. Sta., April, 1896, p. 3.) 89. Forbes, S. A. — On contagious diseases in the chinch bug. (Nineteenth Kept. State Ent. 111., 1896, pp. 16-141; Trans. Dept. Agr. State of 111., 1896; separate, Springfield, 111., 1896, p. 206.) 90. Webster, F. M. — Three years' study of an outbreak of the chinch bug in Ohio. (Bui. 6, o. s., Div. Ent, U. S. Dept. Agr., 1896, pp. 18-25.) 91. Forbes, S. A. — On chinch bug, bacterial disease of chinch bug, etc. (Twen- tieth Rept. State Ent. 111., 1895-96, pp. 35-105.) 92. Webster, F. M. — Chinch bug and Hessian fly. (Agr. Rep. Ohio, 1896, pp. 489-495.) 93. Webster, F. M. — The chinch bug and other destructive insects. (Bui. 77, Ohio Agr. Exp. Sta., Feb., 1897, pp. 32-52.) 94. Stedman, J. M. — Is chinch-bug infection a failure? (Colman's Rural World, March 4, 1897.) 95. Webster, F. M. — The chinch bug. (Bui. 15, o. s., Div. Ent, U. S. Dept. Agr., Nov., 1898, p. 82.) 96. Webster, F. M.— The chinch bug. (Bui. 106, Ohio Agr. Exp. Sta., April, 1899, pp. 237-248.) 97. Irvin, N. a. — How to destroy chinch bugs. (Trans. Miss. Hort. Soc, 1899, p. 406.) 98. Bruner, Lawrence. — Chinch-bug inoculation. (Neb. Farmer, July 19, 1900.) 99. Marlatt, C. L. — The principal insects of growing wheat. (Farmers' Bui. 132, 1901, U. S. Dept. Agr.) 100. Bruner, Lawrence. — The chinch bug. (Neb. Farmer, 1901, p. 441.) 101. Washburn, F. L. — Insects notably injurious in 1902. (Bui. 77, Minn. Agr. Exp. Sta., Nov., 1902; Seventh Ann. Rept. State Ent. Minn., 1902.) 102. Webster, F. M. — An eight years' study of chinch-bug outbreaks in Ohio. (Proc. 22nd Ann. Meet. Soc. Prom. Agr. Sci., 45-57, 1892.) 103. Parrott, p. J. — Chinch-bug fungus distribution. (Journal of Agr., July 10, 1903.) 104. Stedman, J. M. — Status of chinch-bug disease. (Prairie Farmer, Dec. 22, 1904.) 105. Webster, F. M.— The chinch bug. (Bui. 69, Div. Ent, U. S. Dept. Agr., 1907.) 106. Webster, F. M.— The chinch bug. (Cir. 113, n. s., Bur. Ent., U. S. Dept. Agr., 1909.) 107. Univ. of Kansas. — (Circulation of directions to farmers for the infection of fields with chinch-bug disease, 1910.) 108. Headlee, T. J. — The present status of the chinch bug. ( Kansas Farmer, V. 48, June 11, 1910, p. 145.) 109. Parker, J. B.— Chinch bug. (Cir. 5, Kans. State Agr. Coll. Exp. Sta., 1910.) 110. Thorn, Chas. E. — Fighting the chinch bug. (Press Bui. Ohio Exp. Sta., Wooster, Ohio, May 12, 1902.) o LB '12