' pijjSTj ii • Circular No. 21, Revised Edition. United States Department of Agriculture BUREAU OK ENTOMOLOGY L. O. HOWAKD, EntomolouUt and Chief of THE BTB1WBEBBT WKKV I'.;. 1'. II. ' in (,i mi; m. vi'i'i \i: w« i \m> \ \i i 1:1: Ol \TTAi of the strawberry expand they are them from tlic stem. This Fio. 1.— St ra wliTry ; .1 nJfcoi liffnalii'r. \<\\;<< He. Qnatlyenl "mr's lllust r.i- Uon). Just before the blossoms attacked by an insecl which severs inaecl is the strawberry weevil, and the severing of the buds is accomplished by the female in the process of oviposition. The weevil lir>t deposits an m the bud and then punctures or cuts the stem below it bo that in a few days it drops to the ground. Within the severed bud the larva hatched from this develops, and transforms to the pupa and afterwards to the beetle. The strawberry weevil measures only a tenth of an inch in length, and is provided with a slender, slightly curved snout, about half as long as the body, to which are attached its jointed anteniuc The color varies from nearly black to dull red. and each elytron or wing-cover is ornamented jusl be- hind the middle with a dark spot surrounded with whitish pubescence e figs 1 and 2). The presence of the weevil in strawberry beds is manifested by the decreased number of blossoms and the severed buds and steins, the diminutive size of the beetle protecting it from general observation. Nor is the destruction of the buds likely to be noticed until some time after the insect has been at work. Heine it happens that injury, even over wide areas, is often attributed to hail, frost, or to some other cause than the right one. Appearing, as the insecl bo often does, in numbers almost from the outset, its injuries arc se- vere even in seasons when only a moderate percent- :' a crop is 1"-'. because the blossoms chiefly in- jured are the earliest, and eon-eo.uenUy (ije short is largely in the early fruit, or that which coinrai 0M market price. l— Cir. 21 < ■ il (AiUhono- mu.' ifrom Ilil' FOOD PLANTS AND RAVAGES. Fortunately the weevil is restricted to the staminate varieties of the strawberry and to such pistillate varieties as are imperfect and furnish a considerable quantity of pollen, since it is this substance that constitutes the chief food supply of both larvae and adults. This explains the well-known preference of the insect for such varieties as the "Sharpless," "Charles Downing," "Jessie," and 'Wilson." Among imperfect pistillates "Crescents" are often attacked. A frequent source of damage is by the destruction of the staminates used in the fertilization of the pistillates, the product being dwarfed and unsalable fruit. The susceptibility of different varieties appears to be in direct proportion (1) to the quantity of pollen produced and (2) to the amount of exposure of the buds and flowers to the sun. It is fortunate also that this weevil, like so many other trouble- some species, is more or less intermittent in its attack, appearing in great abundance for one or more seasons in certain districts and doing a vast amount of damage, and then without any apparent reason relapsing into comparative obscurity only to reappear after a number of years and in perhaps some new locality. This insect does not confine itself to the cultivated strawberry, although this appears to be its favorite food, but attacks in like manner wild strawbeny, blackberry, dewberry, and occasionally the black-cap raspberry. The buds of the common yellow-flowered cinquefoil (Potentilla canadensis) and of the red-bud tree (Cercis canadensis) are similarly destroyed by the weevil. All of the above- mentioned plants serve as food for the larva. The beetle frequents also other flowers for feeding purposes. It is a lover of light and warmth and works most actively during bright, sunshiny days. DISTRIBUTION AND INJURIOUSNESS. The strawberry weevil is a native species and widely distributed. Its present known distribution includes Canada from Prince Edward Island to Alberta, the Atlantic States, and a portion of the Southern States, and it probably occurs in all of the Middle States. Its precise limits southward and westward have not been ascertained. At present it occupies what are known as the Upper Austral and Transi- tion zones and a portion of the Boreal zone. This weevil was first noticed as injurious in 1871, at Silver Hill, Md. In the next twenty years injuries were reported during different seasons in localities in Missouri, Michigan — in both the upper and lower peninsulas — Staten Island, New York, the Provinces of Ontario and Quebec in Canada, Pennsylvania, and Virginia. From that time until the present (1908) rather general injur}- has been noted in the [Cir. 21] ' berry-growing portions of Virginia, Maryland, North Carolina, and Delaware, ami instances of attack hawe been reported from New Hampshire, southern Nem Jersey , Pennsylvania, New York, Connecti- cut, Rhode Island, Arkansas, and Texs Ajb previously intimated, many fruit-growers are so little familiar with the strawberry weevil thai ourexacl knowledge of its injurious- ness i> limited to reports from correspondents who have the worsi experience with this pest. It is fairly positive that the strawberry, and occasionally the blackberry crop, of Maryland and Virginia is annually levied upon l>\ this pernicious little creature at a rate of from .") to 20 per cent . a loss I hat would seldom l>e fell . or. if no! iced. might not be attributed to this weevil. We have creditable informa- tion that such lias Keen the condition in Virginia since about l sss , and in Maryland since 1885. Dr. James Fletcher, Dominion ento- mologist, states that he ha- occasional reports of injury by this insect everj year in Canada. The greatest amount of loss from t he St raw hen \ u ee\ il w as reported in 1892, when a shortage of two-thirds of the yield in portions of Maryland and Virginia was incurred, a considerable proportion of which was without doubt referable to this insect. In 1896 half of the -t rawberry crop of Mai \ land, according to W. < i. Johnson's estimate, was destroyed. In 1898 a less serious outbreak occurred, injury being mosl pro- nounced in Delaware and Maryland. In 1902 the insect returned in numbers to the same district. In 1904 the injury to the Btrawberry by this species in North Carolina was estimated at $100,000, the i varying from 10 to 50 per cent. Considerable injury in that State has been reported during 1908; in Columbus County and vicinity a irtage of 50 per cent was estimated, from which the money l< was placed at $700,000. NATURAL HISTORY AND HABITS. At. or a few days before the time of the first blooming of the earliest staminate varieties of -t raw berry, this weevil emerges from its winter quarters and Hies to the nearest flowers and Btrawberry beds. Tin- period begins in the latitude of the District of Columbia a- early some seasons a- the middle of April, hut farther north the in doe- not appear until May. The beetles evidently continue to issue from their places () f hibernation for at lea-! a month, though their principal damage is done during the first two or three week-. After feeding and making provision for the continuance of their species the iplaint.-; are sometimes made of this species in tin- Rocky Mountain n tally in Montana, but the culprit in <\\ch cases is undoubtedly a r may not survive in sufE cient numbers to be troublesome in the ensuing year. The ies thus far hied from severed buds are Sigalpkus tibiator --.. Bracon antho- nomi Ashm.. i 'atolac- eiM atdhonomi Ashm. and ( '. inn r- Ashm. T\\() snecies of l)I"e- *"'''■ ' ' ■'"'''" "* 'inthonomi, a par.t.-iic of the strawberry weevil: •I ' Vtlult frmaleaml antenna of male. Greatly enlarged 'origin daceous ants have also been observed, actively engaged in destroying the larva' within the buds, and where ant bills are present in strawberry beds it is probable that few beetles will develop from the buds. The species of ants observed are Formica fusca L. and AphxThogaster fulva R< No insect, bird, or other animal has yet been seen to prey upon th«' adult beetle-. Fowls, even chicks, are of no >ervice whatever. as they roam through infested patches of berries without offering to molest the weevils, which are so small and so quick as apparently to entirely escape their watchful I J [Or. a] METHODS OF CONTROL. The strawberry weevil i- an extremely difficult insect to combat. The very nature of the insect and its life economy enable it to evade most measures that are in successful use against leaf-feeding species. The fact that the larva' live concealed within the buds places the insect, in its earlier stages, beyond the reach of the arsenicals. and the further fact that the adult derives its chief sustenance from the pollen within the buds and does not feed upon the leaves limits the effectiveness of any direct poison. PREVENTIVES. Covering the heds. — Owing to the difficulty of contending with the insect when once it has invaded a strawberry bed, it is necessary to have recourse to preventive measures. A nearly perfect preventive consists in covering the beds. This covering, which may be of muslin or some similar light material, if properly applied will not only exclude the weevil and other noxious insects, but will secure immunity from frost and is moreover a posi- tive benefit to the berries, which ripen a week or ten days earlier and* are superior also in quality and size. Whatever covering is employed should be put in place over the beds at least a week before the appear- ance of the first blossoms and may be safely removed as soon as the first berries are ready for market. Pistillate plants, or those which produce no pollen, require no such protection. Cultivating pistillate varieties. — It is obviously unsafe, in dis- tricts where the weevil is known to be abundant, to trust entirely to staminate varieties of berries. It is advisable, therefore, to grow chiefly pistillate varieties and just as few staminates as are necessarv for the purpose of fertilization. The insects, when they become abundant, will mass themselves upon the staminate plants, where they may be destroyed by spraying and similar measures. For the complete success of this method of culture it is essential that the non-fertilizing plants should be perfect pistillates and bear no pollen. Cultivating profuse-blooming varieties. — According to the general opinion of strawberry growers on the eastern shore of Maryland, as expressed by Dr. F. P. Herr, Ridgely, Md., the most satisfactory method of securing freedom from injury by the strawberry weevil is to plant very profuse-blooming varieties, and many have agreed that the following, in the order named, are the best that have been tested to secure this end: Rio, Superior, Tennessee Prolific, and Gandy.° Trap crops. — In the same manner that the rows of staminates used for fertilization constitute a protection for the other rows, cer- " A. L. Quaintanee. Report .Md. State Hort. Soc, Baltimore. 1902, p. 100. [Cir. 21] tain varieties, particularly Buch as bloom early, may be used to pro- tecl later-blooming plains. One of the besl for this purpose is the "Charles Downing," as it 1 »1* >« » 1 1 1— earl\ and it- blossoms are exposed to the -mi. By laying out beds with "Downings" or other early Btaminates <>n the sides thai experience has shown t" be most sus- ceptible i" attack e.g., in protected sunny Bpots or near wood- land in which the beetles might have hibernated the insects will be attracted From the other portions <>l' tli«' beds and can be the more readily tout rolled by spraying with the arsenicals. The red-bud, which blooms several day- earlier than the straw- berry, attract- the earlie-t arrivals and might al-o -el\ e as a trap. From this tree the insects can lie jarred upon -hect- saturated with kerosene, and destroyed, together with the buds containing the insect's eggs. A- a lure for the neu brood the wild bergamol i- of value. When the hectic- gather upon thi- plant thev may he killed by spraying the flowers or may he captured and destroyed by thousands, thus lessening the chance- of infestation for the ensuing year. For their capture large pan- of water covered with a thin scum of kerosene w ill he found useful. Both red-hud and wild bergamol are ornamental plant-. Clean culture- It i- reasonable to presume that good is always accomplished by clean culture, such a- results from the clearing away of wild or volunteer plants and the "burning nvcr" in early Boring of underbrush and weeds. But in regions where wild straw- berry and blackberry, Potentilla, and red-bud grow in such profusion a- in the neighborhood of Washington, I). ('.. it would appear that little benefit would accrue from such a course. Unsuccessful remedies. A number of remedies that have been tried an 1 found to he unsatisfactory. Capturing the hectic- with a sweep- net has been suggested, hut thi- species i- not readily taken by this method. Among the various substances that have been used in experiment- and found unsatisfactory, either as deterrents or in- secticides, may he mentioned: Lime, ashes, dissolved bone, ammonia in the form of hen manure!, kerosene and plaster, Paris green and plaster, a mixture of "tobacco dust, lime, Pari- green, and coal oil." pyrethrum, whale-oil soap, and a solution of sulphate of copper and lime. Even kerosene emulsion ha- been only partially successful. Pyrethrum has little or no effect when used in the open field. REPELLEN I - .1 good repellent needed. — From the nature of the insect's work it is obvious that whatever is used must he of rapid action. What i- nio-t needed i- i good repellent. For this purpose we would advise [Cir.Ji] 8 a trial with a spray of crude carbolic acid, used in the proportion of 1 part to 100 of water. This preparation has been reported a suc- cessful protection against the rose-chafer in vineyards. Bordeaux mixture. — One of our correspondents has reported some success with Bordeaux mixture, and as this substance has been found effective against other species of beetles, where Paris green failed, it is well worthy of further trial. It affords protection to plants by ren- dering the foliage distasteful to the insects. Bordeaux mixture has the advantage of being a fungicide, for which purpose it is mostlv used, and should the plants be also affected with blight, as is so often the case, it will fulfill a double purpose. In case Paris green is used the Bordeaux mixture should be employed as a diluent in the place of lime and water in the preparation of this arsenical. ARSENICAL SPRAYIXG. The arsenicals, as already stated, can not be depended on to pro- duce as good results as against leaf-feeding insects, for the reason that the adult weevils do not feed on the foliage, and hence may be reached only when they feed on the open blossoms or cut through the corolla of the buds or flower-stems during opposition. The larvae can not be affected at all by any other known insecticide. The arsenicals do not commend themselves to the average straw- berry grower, because of the fear of poisoning the consumer, but ex- periment has shown that there is not the slightest possibility of the poison remaining upon the fruit, since the spray, to have any effect on the weevil, must be applied while the plants are in bud or blossom, the last application being made two or three weeks before the first berries ripen. One of our correspondents has met with sufficient suc- cess with arsenicals to justify further tests. Paris green may be used at the rate of from 1 to 2 pounds of poison to 100 gallons of water, and arsenate of lead at the rate of from 1 to 2 pounds to 25 gallons of water. In their preparation it will be advisable to use Bordeaux mixture as a diluent, particularly if blight is present in the beds. It should also be remembered that the arsenicals act with good success on other insects that may be present on the vines; for example, on the strawberry slugs, leaf-rollers, and the adults of the root-borers. Directions for spraying. — To obtain the best results it is necessary to spray the vines a day or two before blooming, again two or three days after the first bloom, and again five or six days after that, at "Directions for the preparation of this fungicide and the arsenicals here discussed are given in Farmers' Bulletin 127, U. S. Department of Agriculture, which can be obtained gratis on application. [Cir. 21] g [eas! three applications being made al intervals, th< differenl applica- tions being graded with a view to keeping the buds and blossoms cons tan tl) covered with a thin coating of whatever Bubstance is used. Thus, if the variety of berry t.. be treated begins to bloom April _'7, it might be sprayed on the 24th or 25th, again on the 29th or 30th, and a third time, say Ma\ 5. It is doubtful if a f th spraying u,,ultl be profitable, unless more frequent applications be made, except in the event of rain <>r heavy de* fall after spraying, as 1 1 » * - chief damage is done usually during the first two weeks of blooming. The best form of apparatus for spraying garden plant- is a knap- Back sprayer, fitted with the finest Vermorel Bpray-nozzle, bul for larger beds a spray tank mounted <>n a cart or wagon should be used. The periodica] or intermittent nature of this insect has always mili- tated against its successful treatment. Fruit-growers are too prone to "trust to luck" until it Lb too late for the application of remedies with any degree of promise. It should be borne in mind thai what- ever course of remedial or preventive treatment i- pursued musl l>e begun I'ifnn the insect appears. Two week-' uninterrupted work on the part of the insect is sufficient, during it- year- of abundance, so to damage a crop as to make it unprofitable for picking. -i mm \i:i . It may be well to summarize briefly what ha- previously been said under the heading of "Methods of Control." No single remedy will entirely eradicate this in-eet from an infested locality, and after B -trawherrv bed i- mice badly infested the crop can not he saved that year unless remedial measures are at once instituted. Prevent- ives are preferable to direct remedies. These are. in brief, as follow-: (1) Covering the beds with muslin or similar material. See p. 6.) (2) Cultural remedies, including the cultivation of pistillate and profuse-blooming varieties of the strawberry, the use of trap crop-, and clean culture. All of these should he put into operation wherever possible. (See pp. (i and 7.) (3) The repellents advised, and especially Bordeaux mixture mould he given a thorough test. (4) In addition to Paris green, and Pari- green combined with Bordeaux mixture, arsenate of lead should he thoroughly tested, as it may in the end prove to he the best direct remedy. Finally, a good word should he added for the cultivation of pistil- late varieties. These have been thoroughly tested, a- advised on page 6, in Maryland and Virginia in the vicinity of the District of Colum- bia for many year-, with the result that practically no complaints [Cir. 21} 10 of serious injury from the strawberry weevil are now made. This is the result of advice given to all growers in this section who could be reached, they in turn passing on the information to their neighbors. Cooperation is absolutely essential in the treatment of most injurious pests, and the strawherry weevil is a striking example of this. Approved: James Wilson, Secretary of Agriculture. Washington, D. C, June 26, 1908. [Cir. 21] o UNIVERSITY OF FLORIDA 3 1262 09216 4549