/ >/^ aruiiciH I KNTOMOJ I M rri m < i m i i iu. 1 [crlmt. i JoiINSOM 1111(1 \ A GlRAULT, '\ a small -non! I tie of rough sculpture, known as the plum curculio. These beetles issue from thru- winter Quarters aboul the time the trees are in bloom, unci feed on the tender foliage, buds, and blossoms. I .:itrr t h <■ \ attack the newlj set fruit, cutting small cir- cular holes through the -kin in feeding, while the females, in the oper mi ion of egg 1 n \ i ng, make the crescent ic cuts haracteristic of this species. The egg, >le- posited under the -kin oi the fruit, soon hatches into a rery small whitish larva or grub, which makes it- way into the flesh of the fruit Here it f I- greedily and grows rapidly, becoming, in the course of a fortnight, the fat, dirty white ''worm" so well known among fruit growers. The plum curculio is a native of North Ajnerica and for more than one hundred and liftv years has been known as an enemy of -tone fruits. Our early horticultural literature abounds with references to its depredations. In more recent times the great increase in plantings of fruits, brought about to supply the increased demand, has per mitted it to become much more abundant than formerly, and the plum curculio constitutes, at the present time, one of the most serious insect enemies of orchard crops. This species i^ quite generally distributed over the United States east ward of aboul the one hundredth meridian, it- range extending from southern Canada to Florida and Texas. Westward of the State* : n Fie. 1. — The plum eun larva; right "f '■ L/ bordering the Mississippi River it rapidly loses it- importance a a pest, owing probably to the more arid condition of the climate. I. UK HISTORY AM> II VBITS. Like other beetles, the plum curculio has i'our distinct stages in its life, namely, the egg, the larva or " worm," the pupa, and tin- adult <>r beetle. The last three stages are shown much enlarged in figure 1. The in-ccl passes the winter in the adult or beetle stage under accu- mulations oi' partly decayed leaves, among the closely packed dried grass of sod-covered orchard-, and probably wherever suitable protec- tion from the weather may he found. As it- depredations are usually the worst in those portions of orchards which are in close proximity to wood-, the beetles doubtless find the natural accumulation- of rub- bish in such situations very suitable places in which to pas- the winter. In Niagara County. X. Y.. during the fall of 1905, numerous careful searches for beetles were made under leaves and rubbish in plum, peach, and apple orchard- and woodlots and hedgerows adjoining them. These searches did not discover any hiber- nating beetles except in one large apple di- ehard where the ground wa- covered with sod. Failure to find beetles in other place- was probably due to the -canity of the in- sect in plum and peach orchards during the preceding summer. In the sod-covered '#' T apple orchard mentioned, a total of 42 ■~i&W ! * beetle- wa- found at various times between October 14 and November 28. In every case they were beneath partly decayed Fig. 2.— The plum curculio: Adult leavo under apple tree- and often ill de- female on plum, showing the cir- • , 1 -i ■ 1 • ■ .1 1 cularf ling punctures and the P^SSlOnS in the -oil into which the leave- crescentic egg laying punctures, were clo-ely packed. Enlarged (original). t ^i 1 .1 e i 1 1 In the spring, when the fruit buds are unfolding, the beetles begin to emerge from their winter quarter^ and feed to some extent on the blossoms and tender leaves. Mating soon begins, and by the time the fruit i- well set the beetle- make this fruit the child' object of their attention. Figure 2 is an enlarged illustration of a young plum, showing :: female beetle and the char- acteristic feeding and egg-laying puncture- which she has been engaged, with others, in making. The circular punctures are made in feeding; the others are egg puncture-. A single egg i- deposited in a puncture, although several may be placed in a single fruit. From one to eight eggs may In 1 deposited daily by an individual female. Oviposition and feeding continue [Clr. 7.-. I :: for several weeks and in the cu u "i the hardier individuah ma> c\Ii'imI over ii period of -several months. Kgg laying i . however, mosl active (hiring the first four or five week- after emergence of the beetles in spring During recent year? egg laying records for the ea on made in wideh separated localities, shov that the total number of egg depos Med l>\ iIk female varie- widely. In Maryland Professor Quain tance and Mr. K. I. Smith found thai the number \ females of longesl life varied from 276 to 136 \i Washington, I >. ('.. the junior author during the pasl eason obtained records of oviposit ion in plums which showed :i range of from 273 to 560. A record of egg deposition in phi m- w as also made by the senior author in western Nev Vork during the same season, and this showed ;i range of from 76 t<> _'.">!. Professor Crandall, in Illinois, obtained records for apples showing n range of from 18 to 252 for individuals of longesl life. The number of days required for the eggs to hatch varies according to temperature. Records of the pasl season -how that mi Washington, I >. ( '.. the time varies from aboul three to five days, whereas In western Ne\< York il varies from aboul four to seven days. When the larva attains full growth, which requires some twelve t<< eighteen days, it bores its waj out of the fruit and enters the soil. Ai n depth varying from one-half inch i<> 2 inches, rarely much deeper, ii forms an earthen cell in which to pupate. The time required for the pupal stage and the emergence of the normally colored beetle is from three to four weeks. Thus the period of devel opment from egg i<> adull is covered in from aboul five to weeks. Differences in weather and soil conditions, however, cause the time of emergence of the adults to van greatly. When the soil i- mtv dry, the l>eetles may remain in the pupal cell for days or even week- after their normal period of emergence, whereas after a heayj rain they may emerge in numbers. I hus a new generation of beetles from eggs deposited early in the season appear- some time before all the parent beetles have died. In fact, some of the overw intering bee ties have been kepi alive until late in October. Upon emergence from the soil, beetles <'l' the new generation almost immediately turn their attention t>> ungathered fruit, if ilii- be pres er.i on the trees. In < reorgia peach orchards, as observed by Mr. J. I ! . Beat tie, of this Bureau, the beetles attack the foliage in cases where the fruit has been harvested. Prunes, plums, and peaches often suf fer severely, and the injury i- familiar t<> many orchardists as the circular punctures and pits made al the stem end of the fruits, caus- ing tin- latter to rot and drop off a few days before ripening. The work of the new generation of th" curculio is conspicuous on late varieties of apple- also, the beetles feeding upon these until the [Clr. 73] approach of cold weather, when they leave the trees and seek winter quarters. In orchards where sod and other conditions permit the accumulation of leaves and rubbish directly beneath the trees many beetles simply go to the ground, work beneath the leaves, and there pass the winter, and are thus near at hand to attack the fruit when it develops the following spring. FOOD PLANTS. The natural food plant of the plum curculio is undoubtedly the native wild plum. The curculio also feeds upon and breeds in wild crabapples, wild cherries, and haws, and i> reported to breed in the persimmon. It has also been bred from a common fungous growth of plums and cherries called "black-knot" (Plowrightia morbosa Sacc), though this is evidently an abnormal habit. Of the culti- vated pome and stone fruits, nearly all are attacked for feeding and egg-laying purposes, including plums, peaches, cherries, nectarines, apricots, apples, and pears, but of those listed the smooth-skinned sorts, notably plums, are preferred. The beetle feeds also upon the blossoms and foliage of its various food plants, but to a much more limited extent. CHARACTEB OF INJURY. The plum curculio is injurious in both the larval and adult stages, though it is in the adult stage that it is most harm- ful. The young fruit becomes badly scarred by the more or leti of adults. .1/7'/'. Cureulio injurj to the apple has latch l>een the cause "I considerable complaint. It is much like that done to the plum, though the voung fruit is not -<> likeh to fall i « » the ground when punctured, and the larvae arc probably never able t<> mature in fruit which remains on the tree. The young fruit maj largel} outgrow the » -irir puncture, which may -how In the ripe fruit as a brown and roughened, more or les crescentic spot which does n< »i materially affect its value; l>nt when badly punctured, especially bj feeding of the beetles, the fruit as it grows becomes knotted and pitied. Fall aixl winter varieties maj be seriously injured bj the feeding upon the fruit of beetles of the new generation. Peach. On account of the thick fu//\ pubescence on the young peach, tlii> fruit is perhaps attacked less early than is the plum, but the character of the injury is essentiallj the same. Man\ fall to the ground. Those remaining on the tree-, if badrj punctured, become knotty and misshapen and often exude masses of gum from the wound-. Such fruit will usually ripen prematurely. Ripe fruit which appear- perfectly sound, bul which contains nearh full-grown larva, i- often found on the trees. To all appearances such fruit is in first -class condition and i- thus often shipped to market. Chewy. -In iiiii-i cases infested cherries do nol fall to the ground, the larva- maturing in the fruit on the tree-. Usually but a single larva i> found in a fruit, and infestation i- apt to i_ r <> undetected. Apricot mill /,' ' tm in- . These are usually injured in much the -ame way a- are plum and peach. Isolated tree- loaded with apricot- are often -o badly infested that not a single fruit escapes, /' Cureulio larvae are apparently not able to develop in fruit on the tree-, hence injury i- confined to the egg and feeding punctures made by the adult- when the pear- are -mall. In fruil which does not fall the injury may he quite outgrown, but in cases of excessive puncturing the fruit i- badly warped. \ \ ri i; w i \i \iii-. Under the head of natural enemies are to he mentioned several parasites of the plum cureulio which play a very important role in holding the insect in check. Perhaps the most important of these is a minute hyincnoptcroii- insect belonging to the family Mvmarida-. ICir. ?;:] which attack- the egg, although the latter i- apparently well pro- tected under the skin of the fruit. This insect is known by the scien- tific name Anaphes conotracheli Girault. It is now known to occur in Georgia, North Carolina. Virginia, Maryland, the District of Co- lumbia, Kentucky. Connecticut, Texas, and Indian Territory, and is apparently quite abundant. According to the few observations which have thus far been made, it destroys in Maryland from 16 to 70 per rent of the eggs, and a- the life cycle in June was only nine days, several generations of this parasite must successfully develop in the eggs of the plum curculio, thus increasing it- efficiency. The other parasites attack the larva or grub. They are Sigalphus curculionis Fitch and its variety rufus Riley, and Thersilochus <■<>,,<,- Pig. 4. — Tarring for the plum curculio in a Georgia peach orchard. (Original.) tracheli Riley. The former i> of much more importance than the latter because of its greater abundance. It is a common parasite of several other coleopterous larva- and is quite widely distributed. Limited observations indicate that this parasite destroy- about 20 per cent of the larvae of the plum curculio. Thersilochus conotrachelihas not been met with outside of Xew York State, and the influence it exert- in keeping down the curculio is perhaps very small. Besides the true parasites several predaceous beetles and ants attack and destroy the curculio larvae as they leave the fruit to enter the -oil for pupation. Their value in most cases doe- not equal that of the parasites. [Cir. T:!| Chicken? are said i" help great l\ in destroying tin 1 ciall\ 111 small orchards planted near the liome, i ■ i : i \ i \ i i \ i \i i \m i;i - Although man a methods have been promised for lessening the in iui\ of this |K»rnicions pest, onlj h Few have proved of real value. Jarring. An g these, jarring is the method which is perhaps in hum general use in protecting plums and peaches, and by man} orchardists il is tmlieved to give the best results. Earl} observations upon the plum curculio showed that this insect has .1 habit of falling in the ground and ''playing possum" when disturbed. A knowl fe,Afri . . '* V >■ K \" * ^■**L 1^ " v "" t *I v 'H IfilliP '" • ''■• ■*• Thi in'] in use in larrlng roi the plum cnrculln. (After S edge of this halm has led to the capture of the beetles on sheets held or spread beneath the trees, the trees being jarred by a sudden, for table Mow struck with n padded pole or mallet in order t«i dislodge the beetles. In the spring, about the time the calyx or " shuck " is beginnii ^■lip off from the newh set fruit, jarring is commenced and i- con- tinued daily or as often as the weather \*ill permit for m period of four or five % weeks or until the operation ceases to yield mam beetles. Jarring is best done in the early morning or late evening, for ;ii these tunes tin- beetles are It— active, drop more readily, and are no1 so likely to escape by flying m- crawling from the sheets a- they are al midday. [Clr 7:;| 8 There are several kinds of catchers in common use by orchardists. One form is shown in figure 4 and consists ) . i- a two-wheeled cart upon which is mounted a canvas covering arranged in the form of an inverted umbrella. There is a narrow opening at the front to receive the trunk of the tree. When the catcher is in position, the trunk of the tree is given a sharp blow. This causes the beetles to drop to the canvas, from which they are swept into the tin receptacle, or "hop- per," hanging under the center of the cart directly beneath an opening in the canvas. Some operators place kerosene in the "hopper" to destroy the insects as soon as they fall into it. Others have chestnut roasters placed at the end of the rows, in which the insects and rubbish collected in the " hopper " are finally roasted. Although the operations just described are somewhat laborious and expensive, many orchardists have demonstrated thai the outlay in time and money thus invested will bring profitable returns. Some interesting figures concerning the cost of and results from this work as practiced in a Georgia orchard were obtained by Messrs. W. M. Scott and W. F. Fiske during the season of 1900 and published in Bulletin Xo. 31, new series, of this Bureau. Some 200,000 hearing peach and 50,000 bearing plum trees were jarred about 16 times during the period from April ln 1 1 1 * - plants upon which tln\ lav their eggs, and numerous careful experiments have shown thai they may be poisoned by thoroughly spraying the trees with arsenicals. The results of such work, however, appear to vary somewhat, depending on the relative abundance of the beetles during a given season. Main orchard ists have adopted the practice of -|>r:i\ ing for the curculio in preference to jarring, on account of the labor involved in the latter and the frequency with which the work inii-.t l>c repeated to make it effective. Professor Crandall, in Illi nois," has shown that curculio injurj to apples maj be reduced some •_'i) to I" per cent l>\ a reasonable number of poison applications. The results of persistent spraying by orchardists in western New York arc -ci forth by Professor Slingerland in Bulletin No. 235 of the Cor nell Experiment Station. It is there stated that the growers are almost all in l'a\ or of spraying for the curculio, especially upon plums and cherries. The exact value of arsenicals in controlling the cur- culio on peach has apparently not vet been determined, though there aft- numerous growers who spray their peach trees every year ami report good results. The foliage of peach i- likely to lie injured, however, by repeated applications of arsenical sprays, and the grower using these sprays \'<>r the firal t ime -I ion Id proceed with caution. In local it ies w h«' re it has been established that no injury results from their use, they are to be recommended. Other -tone fruits, while liable to foliage injury from repeated applications of arsenicals, are appar- ently not so sensitive a- i- the peach. I >iu care should be taken at all times that the poison be used as recommended below. Apple and pear are rarely, if ever, injured by the proper use of arsenicals. Of the poisons available, such a- Pari- green, "green arsenoid,' 1 ami arsenate of lead, the latter i- least likely to be injurious and should be used where -tone fruit- are to be treated. Liability to injury from arsenical poisons will he greatly reduced by adding to each •">" gallons of tln> spray the milk bf lime made by slacking •_' or :'■ pound- of g I -tone lime. Where Bordeaux mixture is employed againsl scab and other fungous diseases, the arsenical may be used in the fungicide, and the milk of lime i- then unnecessary. To he reasonably effective in killing the beetles, arsenate of lead should l>e used at the rate of 2 pounds to 50 gallons of water. Paris green or green arsenoid should not. on -tone fruit-, he used stronger than 1 pound to 150 or 200 gal Ion- of water. On pome fruit- a -(•mew hat greater strength may he used without danger of injury to the foliage. Bui. 08, in \-i ■ Exp. Sta., p. 553. [Clr. 7:<| 10 Since the period of feeding and egg laying of the curculio extends over several week's from its emergence in spring, several applications of pOisoil are necessary. The first application should be made as soon as the bloss s have fallen, and three or four subsequent applications should be made at inten als of eight to ten days. In the case of apple the usual two applicat ions for the codling moth or canker-worms -just after petals fall and again within a week or ten days — will answer for (he first two applications against the curculio. In spraying for the cur- culio. too much stress can not he laid on the importance of making the applications as thorough as possible. The effort should he made to cover every leaf, twig, and fruit. Cultivation. — Another vulnerable period in the life of the insect i- that when the larva has reached its growth and has passed into the soil. At a distance varying from one-half to 2 inches from the surface the larva makes a small earthen cell in which to undergo its transforma- tion to the pupa, and. later, to the adult beetle. While these changes are taking place the insect is in a perfectly helpless condition, and the stirring of the soil with a cultivator at this period will doubtless break up the cells, causing the death of many of the delicate pupae. Since cultivation is a necessary feature of orchard practice, effort should be made to carry on a pari of it at a period when a majority of the insects are easily destroyed. Careful observations show that in the vicinity of Washington, I). (_'.. and southward the larva' begin to enter the soil about six weeks from the time fruit trees are in full bloom. In Illinois, according to Professor Crandall, about two months elapse between the period of full bloom and the date at which larva' begin to enter the soil. Since the period of maximum egg lay- ing covers from four to five weeks, there is a like "period when the pupae are in the soil in maximum number-. Cultivations to destroy the curculio should therefore begin six or eight weeks, according to latitude, from the time of full bloom of the trees anil should be con- tinued for foui- or five weeks. Such work could be readily arranged for as part of the regular cultivation given the orchard. Gathering fallen fruit. — The number of curculios can be greatly reduced by picking up and destroying the fallen fruit infested with larvae. Much of the infested fruit falls to the ground several days before the larva is full grown and ready to leave it. If this be gath- ered and" burned, at intervals of three or four days, it will result in greatly lessening the number of beetles to attack the fruit in the fall and following spring. A pproved : James Wilson, S( cretary of Agriculture. Washington, I). ('.. April l' t , 1906. [Clr. 73] O c UNIVERSITY OF FLORIDA 3 1262 09216 4796 ** s