SB foal. e. a. '•W WitXiTwi. 3-^ UNITED STATES DEPARTMENT OF AGRICULTURE BULLETIN No. 643 Contribntion from the Bareaa of Entomolog/ L. O. HOWARD, Chief Washington, D. C. March 8, 1918 THE MELON FLY By E. A. BACK, Entomologist and C. E. PEMBERTON, Assistant Entomologist Mediterranean and Other Fruit Fly Investigations CONTENTS Page What the Melon Fly is Lilce ..... 3 OrifTin and Distribution 4 Establishment and Spread in Hawaii . . 4 Methods of Spread 7 Economic Importance 7 Nature of Injury Caused by the Melon Fly 8 Food or Host Plants 16 Page Interesting Facts Concerning the Adult Fly 22 Why the Melon Fly is a Serious Pest . . 24 Control Measures . . 2S Measures Taken to Keep Fruit Flies of Hawaii from Gaining a Foothold in Con* tinenUl United States 29 Summary SO WASHINGTON GOVERNMENT PRINTING OFHCB 1918 THE MELON FLY is a truck-crop pest that in the course of international commerce has been spread from its native home in the Indo-Malayan region to the Hawaiian Islands, and has become so thoroughly established that it can not be eradicated. Owing to its destructive work, such fruits as musk- melons, watermelons, pumpkins, squashes, cucum- bers, vegetable marrows, and tomatoes can not be grown to-day in many parts of the Hawaiian Islands unless the plants are screened. Cantaloupes and watermelons, instead of being common and cheap delicacies, as in former years, are now a luxury even for the wealthy; and cantaloupes, formerly grown in quantities about Honolulu, are now im- ported from California. Owing to the danger of introducing the melon fly into countries where it does not now exist, quarantines prohibit the export of Hawaiian-grown eggplant, bell peppers, and tomatoes, thus shutting off an income formerly enjoyed by the small farmer. In short, it is not possible to exaggerate the seriousness of this insect under Hawaiian coastal conditions. The problem, however, is not entirely a local one to be fought out by the people of Hawaii. Should the melon fly once break through the Federal quar- antine barriers and become established on the main- land of the United States, it will exact a large annual toll of the truck crops of the South. It is important, therefore, that truck growers learn some- thing about this pest, so difficult of control, in order that they may become actively interested in keeping it out. D. of D, MAR 15 1918 UNITED STATES DEPARTMENT OF AGRICULTURE 1^ BULLETIN No. 643 Contribution from the Bureau of Entomology L. O. HOWARD, Chief jdk^'^U Washington, D. C. March 8, 1918 THE MELON FLY.^ By E. A. Back, Entomologist, a-nd C. E. Pembekton, Assistant Entomologist, Mediterranean and Other Fruit Fly Investigations. CONTENTS. What the melon fly isKke , Origin and distribution Establishment and spread in Hawaii Methods of spread Economic importance Nature of injury caused by the melon fly Food or host plants Interesting facts concerning the adult fly 22 Why the melon fly is a serious pest 24 Control measures 25 Measiu-es taken to keep fruit flies of Hawaii from gaining a foothold in continental United States. IC) Summary. THE MELON FLY is a serious pest that never slioiild have gained access to the Hawaiian Islands. Its establishment in Hawaii came naturally enough, as in the case of many of our worst insect enemies, along with the development of unrestricted modern commerce, and owing to the lack, in earlier days, of a knowledge of pests in other lands likely to be introduced into ours, or of any quickened public opinion which, at last thoroughly alive to the great financial losses that may be averted, is to-day heartily sup- porting Federal quarantines directed against just such pests as the melon fly. The melon fly is now established thoroughly throughout the coastal regions of the Hawaiian Islands and never will be eradi- cated. It attacks many vegetables that otherwise could be grown readily by the poorer people, who are least able to purchase them. Melons, pumpkins, squashes, cucumbers, and tomatoes, and some 1 Bactrocera cucuriitae Coq. ; order Diptcra, family Trypetidae. For a more extended account of the melon fly see Back, B. A., and Pemberton, C. E. The melon fly in Hawaii. U. S. Dept. Agr. Bui. 491. 64 p., 24 pi., 10 fig. 1917. This may be obtained from the Superintendent of Documents, Government Printing Office, Washington, D. C, for 25 cents. Note. — The manuscript of this paper was prepared for publication as a Farmers' Bul- letin, but owing to the fact that it deals with an insect which has not yet been introduced into the continental United States it was considered more appropriate to issue it in the series of Department Bulletins. 18314° — 18 — Bull. 643 1 BULLETIN 643, U. S. DEPARTMENT OF AGEICULTUEE. other A'egetables to-day can not be grown in many parts of the islands except Avith great effort ; they must be imported from across the sea, as a result of melon-fly attack. The melon fly is capable of living and causing damage through- out the warmer portions of the mainland United States. As it is Fig. 1. — Tip of watermelon vine, sliovving adult melon fly laying eggs in ovary of a flower still in bud, an unaffected male bloom, and withered and drooping growing tip of vine. A female melon fly has deposited eggs in the vine at base of leafstalk, and the young larvae hatching have nearly severed the vine at this point. (Authors' illustration.) being intercepted rather frequently by official inspectors at Cali- fornia ports on ships from Hawaii, the importance of cooperation by all in making the quarantine of the Federal Horticultural Board a success in keeping out this very serious pest will be readily appre- ciated. THE MELON FLY. 3 WHAT THE MELON FLY IS LIKE. The melon fly, like other so-called " fruit flies," is similar to the ordinary house fly in some respects ; the adult lays small white eggs from which hatch larvae, or maggots, which when full grown trans- form into pupa3. Later the adult emerges from the pupa, as the butterfly does from the chryalis, and the cycle of life — adult, egg, larva, pupa — is repeated with each successive generation. Fig- ure 1 shows an adult melon fly about to lay eggs in the bud of a watermelon. Note the relative size of the fly and the bud. The adult female, greatly enlarged, is shown in figure 2. ^Vlien it is remembered that the adult is from one-fourth to one-third of an inch long, that its body is of a A^ellowish to a yellowish-brown color, Fig. 2. — Adult female of the melon fly. Greatly enlarged. (Authors' illustration.) and the markings between the wings, which appear white in the figure, are bright canary yellow in the living insect, and that the wings are banded Avith dark brown, it will not be difficult to recog- nize this pest. The female fly drills small, pinhole-like openings in the skin of vegetables with the sharp tip of her body, called the ovipositor. Through these punctures she lays her white eggs, Avhich are about one twenty-fifth of an inch long. If a small squash flower be cut open after the female fly has laid her eggs, a small cavity containing the eggs, such as is illustrated by figure 3, is shown. The larvse, or mag- gots, that hatch from the eggs feed in various parts of the host plant. They have two black hooklike processes in the head that serve as jaws in aiding them to break up their food and to force their way BULLETIN 643^ U. S, DEPARTMENT OF AGRICULTUKE. through the phxnt tissues. But as the hirvse, even when full grown, are only about two-fifths of an inch long, a detailed description of them is of little value. It is enough to know that they differ very little from the ordinary white maggots, of equal size, with which the reader is doubtless familiar. The larvae when full grown leave the host to transform to the pupa stage just beneath the surface of the soil, or beneath any protecting object. They even may transform to the pupa within the host fruit, but this is a rare occurrence. Figure 4 shows larvae and pupae about twice natural size. In figure 6 are shown well-grown larvae feeding in the root of a young watermelon plant. Figure 5 represents an enlarged larva. As the melon fly usually first forces itself upon the attention of the market gardener by the dam- age it does, it is more important to be able to recog- nize it by its work than by a mere description of the different stages. The reader, therefore, is directed particularly to the illustrations, for, be- sides showing types of injury, they make clear that it is in the lars^a stage that the melon fly causes its greatest damage. ORIGIN AND DISTRIBUTION. The original home of the melon fly is the Indo- Malayan region. At present it is known to occur in various parts of India, in Ceylon, Java, Macao, Timor, northern Australia, about Singapore, in southern China at Canton and Hongkong, in the Philippine Islands, in Formosa, and in the Ha- waiian Islands. There is some doubt at present about its occurrence at Nagasaki, Japan. It is believed that the melon fly was introduced into the Hawaiian Islands at Honolulu from It probably arrived in the larva stage in vege- tables brought along as food from Japan by Japanese coolies emi- grating as steerage passengers to work on the sugar plantations in Hawaii. ESTABLISHMENT AND SPREAD IN HAWAII. Fig. 3. — The melon fly : a. Eggs de- posited in cavity In young pumpkin flower ; h, single egg, much en- larged. ( Authors' illustration.) Japan or China. The melon fly was first observed in Hawaii, so far as records show, by Mr. Byron O. Clark, who, during October to December, 1897, found it almost impossible to grow cucumbers, squashes, melons, and similar vegetables in the Kalihi district of Honolulu and about Pearl City. During August, 1898, the pest already was established at Lau- THE MELON FLY. 5 pahoehoe, Island of Hawaii. Indications are that the melon fly was introduced as early as 1895. That the melon fly is an introduced pest is proved by the inter- esting fact that the gourd calabashes used by the Hawaiian natives during the past century, many of which are preserved in various Fig. 4. — Melon fly: a. Well-grown larva;; b, puparia. Twice natural size. (Original.) Fig. 5. — The melon fly : Third-instar larva, a. Lateral view of entire body ; b, dorsal view of anterior end ; c, d, lateral and ventral views of same. Much enlarged. (Authors' illustration.) museums and private collections, are free from evidences of melon- fly attack. Modern utensils largely have superseded calabashes dur- ing these later days, but the few that are gi'own show the surface defects due to the attack of the melon fl}^ Although no satisfactory record has been made of the spread of the melon fly to the various islands of Hawaii, it is now a well- BULLETIN 643, U, S. DEPARTMENT OF AGEICULTUEE. Fig. G. — 1, Watermelon seedling destroyed by larvffi of melon fly foodins in taproot, crown, and leaf petioles; 2, work of larvae in root, enlarged. (Authors' illus- tration.) THE MELON FLY. 7 established and serious pest throughout all the coastal regions. It has been known even to attack cucumbers and squash at altitudes ranging up to 4,000 or 4,500 feet. METHODS OF SPREAD. The melon fly probably is carried more often from one locality or country to another in the larva stage than in any other form. Quarantine officials at San Francisco have found living larvsc in host fruits arriving at San Francisco on ships from Honolulu, and records prove that the melon fly in the larva stage is able to bridge the six or seven days required by the slower vessels to cover the 2,000 miles between the Hawaiian Islands and California, since infested fruits have been intercepted and condemned at least once a year since 1912. Host fruits taken on board ships as ship's stores are capable of carrying the melon fly as larvae, or later as pupae, in the fruit containers, for voyages occupying a longer time than is re- quired to cross the Pacific Ocean, and thus may become a factor in spreading the pest through vessels plying between almost all coun- tries where climatic conditions are favorable for the establishment of the fly. The spread from one country to another at a considerable distance probably starts with the fly in the larva stage, but the spread from town to town, or over short distances, as between islands of the Hawaiian group, may occur in the adult or pupa stage. A female fly has been observed to alight on an automobile top and be carried 16 miles from the country into the city of Honolulu. On another occa- sion an adult was seen flying about an interisland boat en route from Honolulu to Hilo, on the island of Hawaii. This fly was not observed after the boat weighed anchor at the port of Lahaina, on the island of Maui, or 72 miles from Honolulu. These two instances will ex- plain the spread of the pest, in the adult stage, about the islands of Hawaii, even if it could not be transported in the larva stage. When larvae form their puparia on bare surfaces, and particularly on a cloth surface, the puparia may adhere sufficiently well to make it possible for them to be transported considerable distances under favorable circumstances. Although no definite instances are known where the melon fly has been spread thus, distribution in this fashion is quite feasible and to be expected. ECONOMIC IMPORTANCE. The melon fly is the most important pest of varieties of melons, squashes, and curcurbits in general grown in the Hawaiian Islands, and probably elsewhere. Its persistent attack has caused many per- sons to abandon the growing of the more susceptible host fruits. 8 BULLETIN 643, U. S. DEPARTMENT OF AGRICULTURE. Other fruits can be grown for the most part only under cover and at increased cost. The unrestricted cultivation of fruits and vegetables in Hawaii has been ruined by the melon Hy and the Mediterranean fruit fly. Though the latter is probably the more to be feared, many persons regard the melon fly as of greater im- portance from an Hawaiian standpoint, for it attacks with the gi'eatest persistency such crops as squashes, pumpkins, vegetable marrows, to- matoes, and beans, all of which could furnish under the ideal Hawaiian climatic conditions an abundance of food for the poorer people. Such vegetables as muslanelons, watermelons, pumpkins, squashes, and tomatoes can not be grown to-day in many parts of the islands unless the plants are screened carefully. Cantaloupes and watermelons, instead of be- ing common and cheap delicacies, as in former years, are now a luxury for even the wealthy. Cantaloupes, once grown in large quantities about Honolulu, now are imported from Cali- fornia. It is no longer possible to grow pump- kins as stock food on idle land. Quarantines prohibit the export of early shipments of egg- plant, bell peppers, and tomatoes, thus shut- ting off an income formerly enjoyed by the small farmer. The loss to market gardeners in Hawaii as a result of melon-fly attack has been placed conservatively at three-fourths of a mil- lion dollars annually. It is not possible to exaggerate the importance of the melon fly as a serious pest under Hawaiian coastal con- ditions. NATURE OF INJURY CAUSED BY THE MELON FLY. Fig. 7. — Older squasb vine with abnormal growths due to work of melon-fly larvje. (Authors' illustra- tion.) The melon fly does not confine its attack to the fruits of its host or food plants. It may attack the young seedling, the flower, the root, the stem, or the fruit. INJURY TO SEEDLING PLANTS- The melon fly attacks with severity the young succulent seedling plants of watermelon and cantaloupe. The female fly lays her eggs in THE MELON FLY. 9 the crown of the plant, and the larvae, on hatching, feed there first. They later burrow down into the taproot and upward into the petioles of the leaves, and even into any young runners that are form- ing. The capacity of the melon fly for injuring a watermelon seedling is shown in figure 6 (p. 6). The enlarged figure of the root shows four full-grown larvae eating their way into the root. In the figure of the seedling the larvae have almost severed the leaf to the left, and have tunneled completely through one of the petioles and so destroyed it that the weight of the leaf has caused its stem to break over. Injury to a seedling runner is shown in figure 8. In cer- tain places in Hawaii where the melon fly is very abundant, entire Fig. 8. — Seedling watermelon showing runner killed back by burrowing melon-fly larvse. (Authors' illustration.) fields of watermelons may be killed before the plants can develop runners. Squash, pumpkin, cucumber, tomato, and bean seedlings almost never are attacked. Larvae never are found in the roots of older plants. INJURY TO THE STEM. As the plant becomes older, it is still subject to attack. The female fly lays her eggs in the rapidly growing pumpkin and squash vines, but the larvae after hatching do very little damage, although they are able to mature. They often cause abnormal swellings or cancerlike spots where a colony of them are feeding, as illustrated by figure 7 ; but if the injury threatens the stem, the plant throws out roots on either side of the part affected to offset the damage. Such attacks upon the stem are not of importance, except in the case of watermelon and cantaloupe. 18314°— 18— Bull. 643 2 10 BULLETIN 643, U. S. DEPARTMENT OF AGEICULTUEE. But in the two plants last mentioned the injury resulting from attack upon the stems may be very serious, and in many cases cause a complete failure of the crop. Figure 9 shows a portion of a canta- PiG y._Cantaloupe vine attacked by melon fly in eight places, including stalk, leaf petioles, and young fruit. (Authors' illustration.) loupe vine that has been attacked in eight places. So persistent is attack upon cantaloupe in Hawaii that the vine can not be grown satisfactorily except in isolated spots or under cover. THE MELON FLY. H Figures 1 and 10 show a common condition found in watermelon fields. The female fly usually chooses the growing tip of the runners in which to lay her eggs. In making a place in the vine for her eggs she practically severs the tip of the vine so that it may fail to grow Fig. lu. — Succulent watermelon vine sectioned to expose five well-grown larvae of tlie melon fly which have eaten out the interior, causing the vine to wither and die back to the point of original infestation. (Authors' illustration.) beyond the point of injury. The growing end of the vine, however, usually is ruined, for, if the egg-laying process does not cause serious damage, the larvse hatching, numbering from 2 to 10, begin to feed and bring about a hasty destruction. Figure 1 shows the drooping, 12 BULLETIN 643, U. S. DEPAETMENT OF AGRICULTURE. withered, growing tip. In this case the eggs were laid just beyond the leaf and flower stalks. When the eggs are laid in the older though still very young and succulent watermelon vine, the larvae, on hatching, tunnel their way Fig. 11. — Melon-fly eggs in blooms of pumpkin. Two buds of the male bloom sectioned to show the eggs doposited through the corolla. (Authors' illustration.) through the vine, eating out the center and causing it to wilt and die. Figure 10 shows a vine sectioned to expose the five well-grown larvae Avhich have killed it beyond the base of the leaf in the upper left- hand corner of the illustration. The serious setback to vine develop- THE MELON PLY. 13 ment that this type of injury causes is readily apparent. Such prun- ing back of the vines, repeated over and again, may prevent the formation of sufficient growth for the development of fruits. INJURY TO THE BLOOM. Although injury to the seedling plant and to the growing stem is greatest in watermelon and can- taloupe and is of little importance among squashes, encumbers, and pumpkins, the injury to the bloom is very serious among all these crops except that of the cu- cumber. Among pumpkins and squashes both the male and fe- male blooms are affected; but among the watermelons, canta- loupes, chayotes, and Chinese marrows the male or staminate bloom escapes attack. It is not uncommon to examine luxuri- antly growing fields of squashes and pumpkins during the warm months and not find a single un- affected bloom. Uninformed growers often question why their vines set no fruits. The condi- tion of the blooms illustrated in figures 11 to 14 is the answer. The unfertilized ovaries of all cucurbit blooms are especially attractive to female melon flies. The flies lay eggs in the undevel- oped and unfertilized ovaries of the bloom before the blossom un- folds, and the larvae, on hatch- ing, often so ruin the ovaries, as indicated by their burrows shown in figure 12, that the flower never unfolds. In those varieties having long, narrow fruits the ovaries arje man}^ times so eaten out and decayed that the weight of the upper part of the bud causes the ovary to break (see fig. 13) . So complete is the destruction Fig. 12. — Work of melon-fly larvae in bring Ing about destruction of ovaries of pumpkin bloom even before the corolla has entirely withered. 14 BULLETIN 643, U. S. DEPARTMENT OF AGRICULTURE. of the ovaries of watermelon bloom that in dry weather the remains of the bloom wither and become minnmified, as shown in figure 15. An examination of the bnds of the male bloom in any field through- out the coastal regions of the Island of Oahu, particularly during the months from March to November, will reveal the severity of attack centered on this portion of the plant. Wherever the buds have been attacked, a whit- ish gumlike excretion exudes which hardens about the point of attack. On cutting the buds lengthwise, batches of eggs can be seen among the folds of the corolla, or in the stamens and receptacle, as shown in figure 11 (p. 12). As the eggs are pure white and are in clusters of 2 to 10 or more, they are seen easily with- out the aid of a lens. If the eggs have been laid from 2 to 6 days, the inside of the bud may have been already eaten out by the rap- idly developing larvsB. Buds attacked before they are half grown usually are destroyed com- pletely before the blossom unfolds. Figure 11 shows three stages in the destruction of the staminate bloom. The bud « is a mass of decay within ; the stamens have been devoured and the larvae already have begam to burroAV about the base; h shows a bud that has been severed by the feeding of the larvae and nas fallen over under its own weight; and c is the upright stem of the bud, after the essential parts of the bloom have been ruined and have fallen to the ground. Although attack may occur so late in the development of the male bloom that the corolla can unfold, it is more often than not that eggs, or even young larva?, can be seen on the inside of the corolla when the flower is in full bloom. The melon fly never attacks the bloom after the corolla has unfolded. Fig. 13. — Pistillate bloom of squash in which larviE of the melon fly have so de- voured the unferti- lized ovary that the bloom is destroyed be- fore the flower can unfold. (Authors' illustration.) INJURY TO NEWLY SET FRUITS. The greatest destruction among fruits usu- ally occurs when they are very young, either before they are fertilized or just after they have set. At this stage of development the young fruits are expanding very rap- idly. Figure 16 shows the damage done to thrjee young pumpkin fruits. About the damaged areas calluses are formed by the fruit in an attempt to repair the damage, but this attempt seldom THE MELON PLY. 15 prevents secondary decays from starting, and these bring about the destruction of such portions as escape the hirvse. The sectioned pumpkin in figure 17 shows how a colony of larvae may eat into a young fruit, become full grown, and leave it without causing a com- plete destruction. It also shows how smaller, weaker colonies may develop in the outer portion of the pulp. INJURY TO OTHER FRUITS. Complete destruction of fruits by larvae of the melon fly rarely occurs after they have become 4 to 5 inches in diameter, for then Fig. 14. — Buds of male flowers of pumpkin damaged by larvae of melon fly, a, h, and c representing various stages in tlie destruction of tlie bloom. (Authors' illustration.) the portion of the fruit containing the seeds, or the part preferred by the larvse, is w^ell protected by the outer meaty pulp and by the rind. Such colonies of larvae as are then able to become established in pumpkins and squashes usually develop in the outer portions of the fruit and do not penetrate to the center. In cantaloupes, water- melons, cucumbers, and marrows, however, the larvae more easily may work their way down to the softer, central portions and there com- plete their development, while the outer portion of the fruit remains quite firm. Figure 19 (p. 20) shows the cross section of a water- melon that had the general external appearance of being sound. 16 BULLETIN 643, U. S. DEPAETMENT OP AGRICULTURE. Yet, when cut open, it Avas found that its center had been eaten away entirely and the well-grown larvae had made tunnels, shown some- what reduced, throughout the rind. Numerous similar examples of destruction might be described. But it is important to remember the fact that melon-fly attack upon the older fruits is far more likely, except in the case of the canta- loupe, cucumber, and tomato, to result in larval development in open surface wounds and in deformities. One of the squashes of figure 21, the cu- cumbers of figure 18, and the watermelon of figure 20 illustrate types of deformities very common in Ha- waii. Wherever the fruits have been only slightly damaged by melon-fly attack, de- formities ; result. It is seldom that a per- fectly formed cucur- bit is seen in the markets of Honolulu unless the fruit was grown under protec- tive coverings. Al- though deformities do not completely ruin the fruit, they restrict development and prevent the fruit from reaching its normal size, as illustrated by the unaffected squash and the badly deformed squash of figure 21 (p. 22). Cucumbers and watermelons so badly deformed as those shown in figures 18 and 20 are not salable, even though they contain no larvae. The purchaser of finiit has learned from experience that deformed cucumbers must be viewed with suspicion, for, although they may be fit for the table, they may contain maggots. FOOD OR HOST PLANTS. The food or host plants of the melon fly may be divided into those preferred and those occasionally infested and may be listed as follows : Fig. 15. — Soction of watermelon vine, showing two fruits so devoured by larvaa of the melon fly that they have become mummified during dry weather following attack. Note that the remains of the blossom still persist. (Authors' illustration.) THE MELON FLY, 17 1. Cantaloupe. 2. Watermelon. 3. Pumpkin. 4. Squash. 5. Gourds. 1. Eggplant. 2. Water lemon flora sp.). 1. Sycos sp.- ]. Kohlrabi. (Passi- CULTIVATED. Preferred. 6. Chinese cucumber {Momordica sp.). 7. Chinese melon. S. Chayote. 9. Cucumber. Occasionally infested. 3. Orange. 4. Fig. 5. Papaya. 10. Tomato. 11. String beans. 12. Cowpeas. 6. Peach. 7. IMango. 8. Citrullus (.Tava). WILD. 2. Momordica sp. Erroneously recorded host fruits. 2. Cabbage. 3. Peppers. CUCURBITACEOUS PLANTS. All the cuciirbitaceous plants are subject to severe infestation, particularly of the young fruits. Cantaloupes are the most susceptible, since the Amines as well as the fruit are attacked badly at all stages of growth, and the fruits do not appear to develop the resistance to attack found among the older watermelons, pump- kins, and squashes. Ordi- narily the cucumber is resistant to attack when very young, although it is rare that cucumbers of- fered for sale in Honolulu do not shoAV some evidence of attack, even w hen very carefully collected. Cantaloupes and cucum- bers may be used success- fully by the female fly for egg laying up to the time Fig. 16. — Various deformities of very young pump- kins caused by infestations started before or just after fertilization of the ovary. These fruits per- sist for a time, owing to calluses developing about points of attack, but they never reach a much larger size and are ultimately destroyed by fungi and secondary attack. (Authors' illustration.) 18 BULLETIN G4;j, U. S. DEPARTMENT OF AGRICULTUEE. of un- not to they are ready for market. Although cantaloupe growing has been abandoned practically in Hawaii since the advent of the melon fly, cucumbers are grown without protection of any sort. Practically all fruits reaching a size fit for salad use show evidences of attack at one or more spots, but the i^ercentage fruits rendered marketable is large enough force the oriental growers to cover the young fruits, although it would appear disastrous^ large to American market gardeners, who place a high value on their time. During midwinter 150 out of 153 cu- cumbers, ready for the market at Moi- liili, were found in- fested varioush\ All cucurbits grow with such rapidity in Hawaii that the oriental is willing to permit the pest to destroy fully 50 per cent of the fruits rather than go to the expense of covering each fruit as soon as or before it sets. To prevent wholesale in- jury, all cucurbits except cucumbers must be covered be- fore or just after blooming. Aside from the fact that the seedlings and vines of all cucurbits except canta- loupe and watermelon are attacked but slightly, there is little differ- ence in the susceptibility to attack of the young fruits under Fig. 17. — Cross section of young pumpkin, showing worlt of larvae of melon fly. Each affected area represents the location of a colony of larvae. (Authors' illus- tration.) THE MELON FLY. 19 Hawaiian conditions. Inasmuch as the fly has been permitted to increase unchecked since its introduction, it has become so abundant that slight differences in inherent resistance to attack are not evident Fig. 18.— Damage to cucumbers by larva? of melon fly. (Authors' Illustration.) among host fruits growing in the field. The infestation is ex- cessive in all unprotected fruits. If by chance pumpkins, squashes, and watermelons escape infestation until they are from 4 to 6 inches 20 BULLETIN 643^ U. S. DEPARTMENT OF AGRICULTURE. in diameter they may reach maturity, although before they reach maturity pumpkins and squashes may support numerous colonies of larvae in open surface wounds and become badly deformed. Out of 254 nearly full-grown pumpkins growing at Kahuku during the winter months, 250 were found variously deformed. As many as G50 adults have been reared from a pumpkin not more than 4 inches long; the staminate bloom while still a bud may support as many as 37 well-grown larvae. TOMATOES. Tomatoes are very susceptible to attack. All tomatoes offered for sale in Honolulu are likely to be infested, as shown by the reports of Fig. 19. — Cross section of young watermelon, showing destruction of interior by larvae of melon fly. Reduced one-fourth. (Authors' illustration.) the market fruit-fly inspector covering several months. Fifteen ripe or partly ripe fruits examined at Hauula on March 21, 1915, con- tained eggs or larvae. Such severe infestation is so general during the warmer months that data are superfluous. Under climatic condi- tions less favorable for the increase of the melon fly the tomato probably would be found to be less susceptible to attack than cucur- bitaceous crops. The fruits of the small wild tomatoes and the spiny yellow-fruited Solanum, common in Hawaii, all are found growing about fields of cucurbit aceous croj)s, but never yet have been found infested. During January and February fields of tomatoes may pro- duce a large percentage of sound fruits, owing to the effect of the THE MELON FLY, 21 cooler weather upon the activities of the fly. Only the fruits of the tomato are subject to attack. STRING BEANS. The ordinary varieties of string beans grown on the mainland as a rule are not infested by the melon fly. Of the variety commonly known as the Yellow Wax bean, 375 pods sufficiently ripe to have turned color were ex- amined at Haleiwa and were found free from attack, although grow- ing close to a field of badly infested pump- kins, in March. Exami- nations of string beans in other localities, par- ticularly about Hono- lulu, indicate that seldom are any of the varieties infested ex- cept the more fleshy, long-podded Chinese variety. This varietj'^ may be attacked very badly when grown near other favored host fruits or on land recently cleared of such crops, as illus- trated by figure 22. As many as 36 well-grown larvae have been found within a single pod. Although the Chi- nese variety is the only one at times generally and badly affected, beans of all varieties except the Lima bean should be included in quarantine lists. The Lima bean never has been found infested. Only the pods of beans usually are infested. The larvae prefer to feed upon the fleshy por- tions of the pod, but sometimes attack the seeds. In badly infested pods, attacked before the seeds are well grown, the larvae may eat out the seeds and leave nothing but the outer portion untouched. This also is true of cowpeas. Fig. 20. — Deformed watermelon resulting from late in- festation by larvse of melon fly. (Authors' illustra- tion.) 22 BULLETIN 643^ U. S. DEPARTMENT OF AGRICULTURE. COWPEAS, Although cowpeas are not grown to any great extent in Hawaii, they are subject to melon-fly attack. Only the pods are affected. As many as 37 larvae have been taken from a single pod. When infesta- tion occurs early the young seeds may be devoured, but attack is cen- tered more often upon the pod itself. Some varieties of cowpeas appear to be less liable than others to attack by the melon fly. FRUITS AND VEGETABLES THAT ARE SELDOM OR NEVER ATTACKED, Several observers have stated that the melon fly attacks eggplant, bell peppers, cabbage, and kohlrabi. During a period of three years the representatives of the department have not found any of these vegetables af- fected. The Mediter- ranean fruit fly has been found attacking eggplant and bell peppers, but only in small numbers. Even in the laboratory egg- plant was found im- mune to melon - fly attack if the fruits were spund. Adult melon flies, however, wei'e reared from fruits first weakened by decays. Adults have been reared from orange, mango, fig, papaya, peach, apple, and water lemon. These fruits, however, do not serve regularly as hosts of the melon fly. Only in rare instances does the melon fly attack them, and then only slightly. For practical purposes aside from quarantines all the fruits and vegetables listed under this subheading are free from attack by the melon fly, INTERESTING FACTS CONCERNING THE ADULT FLY. The most interesting facts about the adult melon fly center about the length of life and the capacity ta lay eggs, No flies have been Fig. 21. — Damage to squash by larva; of melon fly. Of the two fruits illustrated, the one to the right is normal, and the one to the left, the stunted and deformed fruit caused by melon-fly attack. (Authors' illustration.) THE MELON FLY. 23 known to live longer than 4^ clays without food and water, or longer than 5 days with water but no food. But if they can feed upon plant juices, such as the sap that exudes from cut or broken surfaces of pumpkin vines, cucumber fruits, papayas, etc., or the sap exuding from the breaks made in host plants during egg laying, adults may live many months. One female lived from February 17, 1914, to April 4, 1915, or 13| months. The length of adult life is variable Fig. 22. — Destruction of green bean pods by larvae of melon fly. In a and 6 a por- tion of the pods has been removed to expose larv.T and their work. In a are shown four well-grown larvae. Pods in different stages of drying out after the larvfe have left them are shown in c and d. (Authors' illustration.) under like conditions. From the standpoint of longevity the chief interest centers about the fact that certain adults may live long periods and thus keep the pest alive during seasons when host fruits are not in season. Female flies may begin to lay eggs as soon as 14 days after they emerge from the pupa during the warmer months, when the mean temperatures range from 75° to 79° F. During the winter, at a mean 24 BULLETIN 643, V. S. DEPARTMENT OF AGRICULTURE. n of about 71° F., many adults may not lay until 44 days after emer- gence. The season of the year and the nature of their food have an influence upon the rapidity with which eggs are formed. But once the female fly begins to lay eggs, she may continue to do so throughout life. The largest number of eggs laid by any female in confinement is 687, but 1,000 probably may be. laid by vigorous long-lived flies. While 37 is the largest number of eggs laid by a single individual daring any one day, the number varies, and may be as few as 1. On many days no eggs are laid. Unlike the female of the Mediterranean fruit fly, which lays a few eggs almost daily, the female melon fly lays more eggs per day, but at greater intervals. Thus one fly deposited 14, 19, 13, 29, 16, 19, 16, 12, 17, 7, 9, 16, 7, 12, 37, 25, 24, 21, 28, 6, and 18 eggs, respectively, per day during the first three months (summer months) after depositing her first eggs; she laid no eggs in fruits until she w^as 51 days old, and, after she began laying, laid eggs on only 21 out of 90 days. During the seventh, eighth, and ninth months of her life (winter months) she deposited 10^, 2, 18, 14, 15, 20, 13, 9, and 3 eggs. Female flies can resume normal egg laying after periods of scarcity of host fruits. Females that have not been given an opportunity to lay eggs within fruits for periods ranging from 3 to 9 months after emergence have begun to deposit eggs at a normal rate as soon as fruits were placed with them in the laboratory rearing cages. WHY THE MELON FLY IS A SERIOUS PEST. The melon fly is a serious pest in Hawaii because it finds in the coastal areas a favorable climate and plenty of food. Regardless of the great discouragement due to its ravages, the oriental market gardeners, and others to a less extent, plant its host vegetation in rotation on the same or neighboring plats of ground. No attempt is made to prevent the flies from maturing in infested fruits. The de- caying and infested fruits of the cucumber crop, for instance, are left on the field that is to be planted to tomatoes, or the flies develop- ing from the cucumbers migrate to attack the melons just coming into bearing in the near-by field. No system of control, aside from covering successfully a small portion of the fruit that sets, is prac- ticed. It thus happens that large numbers of adults mature, and, as the climate is favorable, they multiply rapidly. During the warmest Hawaiian weather, when the mean temperature averages about 79° F., the egg, larva, and pupa stages may be passed in as few as 12 or as many as 29 days, according to the individual and its host. The complete life cycle is subject to great variation, according to the THE MELOlSr FLY. 25 longevity of the adult. Since one female fly has been known to live 431 days, it is evident that the complete life cycle from the laying of the egg to the death of the fly may be 443 to 460 days when the im- mature stages are passed during the warmer portions of the year. At an average mean temperature of about 68° F., which is the coolest temperature found in Hawaii where fruits are available in numbers for stud}^, the immature stages are passed in 40 to 45 days. It is difficult to state just what the variation in the life cycle may be in colder climates, but it may range between 3 and 4 months. This rapidity of increase throughout the coastal regions permits from 8 to 11 generations of the melon fly a year, when a generation is considered to extend from the time the egg is laid until the female of the next generation begins to deposit eggs. As the females are capable of living many months and of depositing eggs at frequent intervals throughout life, the generations become hopelessly mixed. It is possible for a female oA'ipositing on January 1 to be still alive and laying eggs the following January along with the progeny of 11 generations of her descendants. It is, therefore, small wonder that the melon fly, under such favorable conditions, swarms through- out the market gardens of Hawaii and leaves little unaffected that is not protected by man. CONTROL MEASURES. NATURAL CONTROL. No agencies at present lire working in the Hawaiian Islands to bring about, even periodically, a very large natural reduction in the abundance of melon flies. The mortality among the immature stages, or among the adults, is not sufficiently high to be of practical value, although sometimes 90 per cent of the larvae may be found dead in certain decaying fruits. In climates colder than that of the Hawaiian coastal areas mor- tality due to cold temperatures will play a particularly active part in reducing the pest. While the cooler weather of the winter months does prolong the period of development throughout the coastal re- gions, the long life of the adult flies and the capacity of females for continued egg-laying make it difficult for market gardeners to benefit to any marked extent from the effects of cool weather if they allow their fruits to remain unprotected. The cooler weather in the more isolated gardens holds down the number of adults and limits their activity to a fewer hours during the day when it is warm enough for them to attack fruits, and in this way makes possible greater success in saving fruits by the use of various protective coverings than fol- lows the use of the same measures during the summer months. 26 BULLETIN 643, U. S. DiEPARTMENT OP AGRICULTURE. PARASITES. Hawaii has no native pajrasi^es that attack the melon fly, but the Hawaiian Board of Agriculture and Forestiy has introduced a para- site from India. This parasite ^ was introduced at Honolulu during the early part of 1916, and has been reared and distributed in large numbers, but it is not known yet whether it will check the ravages of the melon fly in a p^ractical manner. It has become established, how- ever, and promises to be useful. ARTIFICIAL CONTROL. Individual growers of vegetables in Hawaii are likely to be dis- couraged in the application of remedial measures for the control of the melon fly. Host fruits are grown in rotation in the numerous garden spots and market-garden areas chiefly by uneducated orien- tals, who do not appreciate the necessity for a united fight against the fly. The usual custom among these laborers is to permit infested fruits to decay in the field. In certain uncultivated areas the wild Sycos and Chinese cucumbers run wild and furnish fruits in which the melon fly can breed throughout the year, even though no culti- vated crops are grown. This abundance of cultivated and wild host fruits, coupled with a climate favorable for rapid multiplication, produces many adult flies which spread in all directions to render valueless all remedial measures except those that involve protective coverings for the fruits. It thus happens that no artificial control measures have been applied successfully in controlling the melon fly under Hawaiian conditions. The only means now employed to safeguard fruits is that of protecting the 3'oung fruits with some type of covering until they are large enough to withstand attack. Trapping adults has proved a failure, and killing them by spraying thus far has given poor results. If all growers would cooperate systematically (1) in the destruction of the eggs and larva? by submerging infested fruits in water or by boiling and (2) in the destruction of the adults by spraying, the value of spraying with a poisoned bait and of covering the young fruits would be enhanced to a point where either might be sufficiently effective to be recommended as satisfactory. But so long as the cultivation of host plants is largely in the hands of orientals and others who do not appear to be amenable to instruc- tion as modified by western standards, no relief can be expected. Since adult melon flies do not deposit eggs for 2 to 4 weeks after emergence during the summer, and only after relativel}^ longer periods * Opius fletcheri Silv. THE MELON PLY. 27 during the wintea', but feed continuously throughout this period, it is evident that any spray that will kill them before they begin to lay eggs is valuable. A poisoned-bait spray^ containing 5 ounces of lead arsenate in paste form, 2^ pounds of brown sugar, and 5 gallons of water, is very effective in killing adults. This spray, used at the rate of 30 gallons to the acre, was applied by means of a knapsack sprayer. About 2 acres of Chinese melons and cucumbers in a field fairly well isolated, from the Hawaiian standpoint, which means that no host fruits were growing within 500 yards, were sprayed on May 21, 26, and 28^ June 1, 4, 8, 14, and 23 during typical summer weather. Six hours after an application many adults were sluggish and flew with difficulty, but within 24 hours many dead adults could be found among the vines. Although the adults were lessened nu- merically by the spray, the young fruits were punctured as badly at the end of the experiment as at the beginning. Although negative results have followed the use of poisoned-bait sprays in Hawaii, failure has been due to the peculiar conditions sur- rounding the fields sprayed that permit an influx of female flies. Under commercial conditions, where cantaloupes, pumpkins, and watermelons are grown in large quantities in fairly dry climates, it is reasonable to believe that sufficiently good results will follow the use of poisoned sprays to make their application practicable as a method of control. DESTRUCTION OF INFESTED FRUITS. Larvae and eggs may be killed by submerging the infested por- tions of the plant in water, or b}^ burjdng, boiling, or burning. Choice of method will depend largely upon the amount of fruit to be handled and upon local conditions. There is no surer way to kill all immature stages than to boil or burn the fruits. Burning is often expensive, and, when trash in compost holes is depended upon to furnish the fuel, is likely to be unsatisfactory, particularly where, as in Honolulu, the quantity of infested material is so great. Bringing infested fruits to the boiling point will kill all forms. The sub- merging of fruits in ordinary tap water for five days will either kill all larvae and eggs or stop further development. Burial in soil is a satisfactory method, provided the fruits are buried deep enough and cracks are prevented from developing in the earth above the fruits as the latter decay and settle. It must be remembered that just after transforming from the pupa the adults are so soft that they can force their way through very small openings. A crack in the soil extending down to the fruit, even though it be no wider than ordinary blotting paper, is still wide enough to allow the adults to reach the surface and thwart the pur- pose of fruit burial. Adults can not make their way through a foot 28 BULLETIN 643, U. S, DEPARTMENT OF AGRICULTURE. of weil-tamped soil, but have been known to force their way throiigli 2 to 3 feet of dry loose sand beneath which their pupae had been buried. Because burial and burning may be left to subordinates who may not have the interests of the owner so much at heart, boiling or sub- mergence in water is more highly recommended. The larvae will not injure cattle if the fruits are used as feed, but many larvae may escape before they are eaten ; hence this method of destruction is not recommended unless the fruits have a real value as a food. PliOTECTIVE COVERINGS. The protection of fruits and plants by covering with soil, pa,per, or cloth is a great labor-consuming operation, yet this is the only method that will protect under present Hawaiian conditions. Even Fig. 23. — Protecting cucurbits from attack by melon flies. Each fruit (in tliis case of Momordica sp. ) is placed, immediately after it has been fertilized, within a long envelope made of newspaper. (Authors' illustration.) as practiced to-day, less than 25 per cent of all fruits covered, except certain Chinese marrows, are actually saved from attack. In a slightly cooler climate than that of coastal Hawaii a high percentage of the fruits could be saved. As it is, the great attraction of the un- fertilized ovaries of the bloom makes it difficult to put on coverings before the flowers are infested. During the warmer portions of the year the bloom of cucurbits, with the exception of the cucumber, should be protected at least three to four days before the flower unfolds. At present many fruits are covered, but rather indifferently and ineffectively. During April only 9 out of 43 fruits of the Chinese melon that had been covered were sound, while on the same datfe 119 THE MELON FLY. 29 out of 692 young protected watermelons were actually free from in- festation. Certain Japanese growers ward off attack by burying the young fruits in the soil or by surrounding them with straw or trash until they are sufficiently old to withstand fatal attack. In certain light soils cantaloupes are kept buried in the soil until they are ripe and they appear upon the market almost white in color. The most suc- cessful of protective coverings are those shown in figure 24. In this case the Momordica vines are grown over bushes, hence the young fruits can be found easily and inclosed in long cases made from newspapers and resembling envelopes cut across at both ends. These cases are left open at the lower end, but are never entered by the adult flies. MEASURES TAKEN TO KEEP THE FRUIT FLIES OF HAWAII FROM GAINING A FOOTHOLD IN CONTINENTAL UNITED STATES. The Federal Horticultural Board, by means of its Quarantine No. 13, entitled "Mediterranean Fruit Fly and Melon Fly," issued March 23, 1914, is doing all that man can do to prevent the two fruit-fly pests of Hawaii from becoming introduced into main- land United States. The regulations of the quarantine practically have put a stop to the movement of fruits and vegetables from Hawaii. Certain fruits and vegetables, however, such as bananas of the noncooking type, pineapples, taro, and coconuts, and others, when it can be shown to the satisfaction of the Department of Agri- culture that in the form in which they are to be shipped they are not and can not be a means of conveying either the Mediterranean fruit fly or the melon fly, may be moved or allowed to move from Hawaii into or through any other State, Territory, or District of the United States when they have been inspected by the United States Department of Agriculture, certified to be free from infesta- tation, and marked in compliance with the regulations. Pineapples, taro, and coconuts do not support the fruit flies of Hawaii, neither do bananas when shipped according to trade requirements. In prac- tice the quarantine eliminates all shipments of fruit except the four just mentioned, and of these pineapples and bananas only are regu- larly shipped. The enforcement of the quarantine is divided between the repre- sentative of the board in Hawaii and those at the ports of entry to the mainland, notably San Francisco, San Pedro, and Seattle. In Hawaii it is the duty of the inspector to see that the fruit is grown under conditions reasonably sanitary from a fruit-fly standpoint, that each package or bundle offered for shipment is inspected and bears a certificate to that effect, and that transporting companies do not re- 30 BULLETIN 643, U. S. DEPARTMENT OF AGEICULTUKE. ceive for shipment consignments of fruit unless they have received from the Federal Horticultural Board a permit for such action. These permits, which give data on the kind, amount, and origin of fruit, the name and address of consignor and consignee, and dates, are issued in triplicate; the duplicate and triplicate remain* in the files of the transporting compan_y and the Federal Horticultural Board, respectively. The original is attached to the bill of lading accompanying the shipment and no consignment of fruit is permitted to leave the ship at the port of destination unless this permit is pre- sented to the Federal inspector. The duty of the inspector at the mainland ports is to make certain that no express or freight consignments leave ships arriving from Hawaii unaccompanied by the permit above mentioned, and that no quarantined fruits or vegetables are present either in the ship's lock- ers as ships' stores or in the possession of passengers, for all such are contraband after the ship passes within the 3-mile limit of the main- land. The inspector of the port of entry also must receive from each passenger a statement that he has in his baggage no contraband fruits or vegetables. Inspectors also have the right to search the personal belongings of passengers and members of the crew. There seems little danger of fruit-fly pests reaching ihe mainland from Hawaii in commercial consignments of fruit since Quarantine No. 13 went into effect. The greatest clanger at present lies in the careless introduction of the pests hy miinformed travelers who^ with- out appreciating the great fiiw/ifwial losses the' Goverivment is attempt- ing to avert^ persist in concealing ahout their persons and haggage contraband fruits^ or in: sending these hy express or post in packages the contents of which are not stated tT^thfuUy. These are the a.ve- nues of introduction that no law can close thoroughly. To close them, honesty and cooperation with the Federal Horticultural Board on the part of all are necessary. SUMMARY. The melon fly, a native of the Indo-Malayan region, is one of a number of very destructive pests that are likely to be introduced into the mainland United States. The quarantine officers of the Federal Horticultural Board and of California are each year intercepting it in infested fruits at California ports on ships from the Hawaiian Islands. The melon fly was introduced into Hawaii about 1895 by Japanese immigrants in fruits which they brought with them as food from Japan. Before its arrival in Hawaii, cantaloupes, watermelons, toma- toes, and all kinds of cucurbitaceous crops, such as pumpkins, squashes, cucumbers, etc., were grown in large quantities and were THE MELON FLY. 31 cheap. They could be grown in every dooryard. Because of the ravages of the pest, these crops can not be grown now by the average person, and only with great difficulty in market gardens. Many fruits must be imported, and the cost of all has been increased as a result of melon-fly attack. Even cowpeas and string beans may be infested. It is impossible to overstate the destructiveness of the melon fly to cucurbitaceous crops under Hawaiian coastal conditions, where none of these can be brought to maturity except with the exercise of the greatest care on the part of market gardeners. Since there are as many as 8 to 11 generations of the melon fly a year, and the female flies may live to be over a year old and lay eggs throughout life, the pest can multiply very rapidly. No agencies have been found to.be working at present in- Hawaii that bring about, even periodically, a great natural reduction in the abundance of melon flies. No native parasites are known to attack the melon fly, but it is hoped that the parasite introduced from India during 191G may prove effective. In colder climates cold weather will prove a marked and valuable control factor. Predacious enemies and several forms of mortality recorded are of no practical value under Hawaiian conditions. No satisfactory artificial measures have been applied' successfully in combating the melon fly under Hawaiian conditions. Poisoned- bait sprays promise to yield effective results under other cultural con- ditions. In Hawaii these sprays would be effective if they w^ere used consistently and universally, but they are not. At presen^t cucurbits can be grown only by the use of coverings of various sorts for the protection of the very young fruit. Killing the immature stages by submergence in water, by burial in soil, or by boiling are not applied as methods of control, although they are effective when intelligently applied. Artificial methods of control are not likely to prove satis- factory in Hawaii so long as the growing of the chief host plants remains in the hands of uneducated oriental laborers who do not practice clean cultural methods or cooperate in applying remedial measures. PUBLICATIONS OF THE U. S. DEPARTMENT OF AGRICULTURE RELATING TO INSECTS INJURIOUS TO CITRUS AND OTHER SUBTROPICAL FRUITS. AVAILABLE FOR FREE DISTRIBUTION BY THE DEPARTMENT. Control of the Citrus Thrips in California and Arizona. (Farmers' Bulletin 674.) Carbon Disiilphid as an Insecticide. (Fai*niers' Bulletin 799.) Common Meal.vbug and its Control in California. (Farmers' Bulletin 862.) Fumigation of Ornamental Greenhouse Plants with Hydrocyanic-acid Gas. (Farmers' Bulletin SSO.) Fumigation of Citrus Trees. (Farmers' Bulletin 923.) Control of the Argentine Ant in Orange Groves. (Farmers' Bulletin 928.) Spraying for the Contx'ol of Insects and Mites Attacking Citrus Trees in Florida. (Farmers' Bulletin 933.) Citrus Fruit Insects in Mediterranean Countries. (Department Bulletin 134.) The Mediterranean Fruit Fly iu Bermuda. (Department Bulletin 161.) Argentine Ant: Distribution and Control in the United States. (Department Bulletin 377. ) The Citrus Thrips. (Department Bulletin 616.) The Mediterranean Fruit Fly. (Department Buleltin 640.) Some Reasons for Spraying to Control Insect and Mite Enemies of Citrus Trees in Florida. (Department Bulletin 645.) The Argentine Ant in Relation to Citrus Orchards. (Department Bulletin 647.) Preparations for Winter Fumigation for Citrus White Fly, (Entomology Circular 111.) Spraying for White Flies in Florida. (Entomology Circular 168.) FOR SALE BY THE SUPERINTENDENT OF DOCUMENTS, GOVERNMENT PRINTING OFFICE, WASHINGTON, D. C. Kat.vdids In.iurious to Oranges in California. (Department Bulletin 256.) Price. 10 cents. The Melon Fly in Hawaii. (Department Bulletin 491.) Price, 25 cents. Fumigation of Ornamental Greenhouse Plants with Hydrocyanic-acid Gas. (Department Bulletin 513.) Price, 5 cents. Mango Weevil. (Entomology Circular 141.) 1911. Price, 5 cents. Fumigation for Citrus White Fly, as Adapted to Florida Conditions. (Ento- molog.v Bulletin 70.) 190S. Price, 15 cents. Fumigation Investigations in California. (Entomology Bulletin 79.) 1909. Price, 15 cents. Hydrocyanic-acid Gas Fumigation in California. (Entomology Bulletin 90, 3 pts.) 1013. Price, 20 cents. Fumigation of Citrus Trees. (Entomology Bulletin 90, pt. I.) 1913. Price, 20 cents. Value of Sodium Cyanid for Fumigation Purposes. (Entomology Bulletin 90, pt. II.) 1913. Price. 5 cents. Chemistry of Fumigation with Hydrocyanic-acid Gas. (Entomology Bulletin 90. pt. III.) 1913. Price, 5 cents. White Flies In.iurious to Citrus in Florida. (Entomology Bulletin 92.) 1911. Price, 25 cents. Orange Thrips, Report of Progress. (Entomology Bulletin 99, pt. I.) 1911. Price, 5 cents. Red-banded Thrips. (Entomology Bulletin 99, pt. II.) 1912. Price. 5 cents. Natural Control of White Flies in Florida. (Entomology Bulletin 102.) 1912. Price, 20 cents. ADDITIONAL COPIES OF THIS PUBLICATION MAY BE PROCURED FROM THE SUPERINTENDENT OF DOCUMENTS GOVERNMENT PRINTING OFFICE WASHINGTON, D. C. AT 10 CENTS PER COPY 32 i Gaylord Bros. Makers Syracuse, N. Y. PAT. JAN. 21, i90«