7^ . ^r Circular No 38, Second Rev United States Department o( Agriculture, BUREAU OK KNTOMOI.OGY. L. O. HOWARD. KntomolouUt and CI. let of Bureau. I III sol iSH-\ INK HOKKR i Milittiii satiyriniformis 1 1 1 «i i ' I II i ii : i i i m • I \ D iitul Special I 3 DEPOSITORY vl'l'l.AR \N< I \\ l> MM HOD Ol u« 'KK One of the most troublesome of the man} enemies of squashes, pumpkins, and other cucurbits is the squash-vine Inner. In many localities this Bpe- irpasses all other squash in- Bects in point of injuriousness. I damage is due to the larvae bor- ing through the stems, causing them to rot at the affected points and become se^ - ered from the vine, or so injur- ing the vine as t" cause the leaves I'uish-virii- Imt.t m Haiti moth; &. (•mate, with wings folded own on brtol *1 ./. tan-grown larva, in tUu In \ toe; - . papa; /'. pupal ocD. All one-third larger than na( - «). to \\ ill and the plant to die. The presence of the borer feeding within the stem is not apparenl at the commencemenl of the attack, bul soon becomes manifest through the presence of the coarse yellowish excre- ment which it forces from its burrow in the stem and which accumu- lates on the ground beneath, as well a< by the sudden \\ iltingand dying down .if the leave-. Wilting occurs -non after the larv;e have made early publications this «p rallyknoi d ol change ol Dame see writer- article in Bul. 19, n b . \H\ Km., p Tlie preeenl edition ,.i t liis circular is slightly changed from the original, which published April 22 od ir->m the [first] revised edition issued November i f ». 51800 < ir. ::- (»s 2 considerable growth within. From one to half a dozen or more larvae inhabit a stem, and often upward of forty individuals have been taken from a single plant; indeed, one grower has stated that he once cut "142 larvae from a single vine." The Larvae work with great rapidity and in a very short time are able to injure a plant so that no fruit will mature. Injury is most noticeable near the base of the stems, where in course of time the vine becomes severed from the roots and the whole vine dies. Che parent of 'this insect is a beautiful creature, a medium-sized moth of the family Sesiidae, or clear-winged moths. The fore wings are opaque, lustrous olive-brown in color, with metallic green reflections, and expand from less than an inch to nearly an inch and a half. The hind wings are transparent and veined as shown in the accompanying illustration of the male (tig. 1, a). The abdomen is conspicuously marked with orange or red. black, and bronze, and the hind legs are fringed with long hairs — red or orange on the outer surface and black inside. The natural position of the moth when at rest is shown by the figure of the female (b). . DISTRIBUTION. As far as known, the squash-vine borer is a native of the Western Hemisphere, and widely distributed and injurious in the United States practically wherever squashes are cultivated. Available rec- ords and examination of material in the collection of the l". S. National Museum show that it has a range embracing territory from the Xew England States and Canada, in the north, to the Gulf States south- ward, and westward to the region beyond the Missouri River, which comprises the major portion of the Carolinian and Austroriparian areas of the Upper and Lower Austral life zones and a portion also of the Transition zone. Injury has been observed to be particularly severe in recent years on Long Island and in New Jersey. Delaware, Maryland, Virginia, and the District of Columbia, in the East, and in Kansas and Nebraska in the West. Other States in which injury has been noted include Maine. Massachusetts. Connecticut, Rhode Island, Georgia, Alabama. Mississippi. Louisiana, [owa, and Michi- gan. It is evidently of tropical origin, and occurs in Mexico, where it is also widely distributed, and in Guatemala. Panama. Venezuela, Argentina, and the Lower Amazon. FOOD HABITS. The vines of squash and pumpkin form the chief food supply of this insect, but occasionally it attacks also the gourd, muskmelon, and cucumber. It does not, however, in the writer's experience, infest melons and cucumbers when the other preferred crops are available. The larvae bore through the stems from the roots to the base of and [Cir. 38] even through the leaf-stalks, and young larva; ma} be found even in the larger veins, into which the} !►• >n- when the eggs have been placed in mii h locations, and often attack the fruit. The} also penetrate gourds so hard thai it is difficult to cut into them with a sharp knife Larvae have been observed on the wild balsam apple (Echinocy lobata), which isprobabl} a natural t"< >. >< 1 plant. Injur} i- greatest to Hubbard, marrow cymlings, and other lut «■ varieties of squash, and is apt to he more acutely Mi in small gardens than where crops arc grown for market. Even if the plant survives tit tack it may not hear fruit . and often the grower loses a large propoi tion of his crop year after year. Not infrequently entire crops are destro} ed. \ \ i i i: \i HISTi >i:i . This species i> injurious onl} in the larval form. Although the lar\;c arc familiar objects to squash growers, the moths arc not genei all} recognized as t he parents of t hese pernicious borers. The moths, unlike most others, ll\ onl} during the daytime and in the heat of the da} . Tov« ard t w ilight they become less act i\ e and ma} be seen sitting quietl} on the leaves of their host plants. Both when in flight and when at rest the moth- arc Bingularl} wasp-like in appearance. Timt of appearand <>i tl>> moth. Approximate!} it ma} be stated t hat the moth appears as soon a- the \ ines are sufficientl} advanced to serve for oviposition and the subsequent subsistence of the borer larvae within their stems. Indications are t hat a- far south a- t he Dist riet of Columbia the moths make their first appearance in the held some time in May, or at leasl earh in June, a- larvae aearrj matured have been found by the middle of July. In New Jersey, according to Dr. J. B. Smith, the moth- arc.ahroad at or soon after the beginning of. lime; on Long Island, from the middle to the last of June. . In Massachuset t-. according to Harris, they appear about the plants the second week in July. We thus have considerable variation in time of earliesl appear- ance, dependent upon season and localit} a variation to he expected in a species of so wide a range. egg ami oviposition. The eggs, which are oval and dull red in color, are laid upon all part- of a plant, from the root- to the hud- and petiole-, hut chief!} along the stems, although in some varieties of squash, il i- -aid. nearer the base of the stem than otherwise. Ovi- position i- very rapid, the moth flitting from hill to hill, leaving an in each. A single moth ma} la} as man} as 212 eggs. The eggs hatch m from -i\ to fifteen day- after the} are deposited, and the larvae are -aid to attain full growth four or more week- later. This period will undoubtedl} vary in differenl temperatures, according to the season of the year when oviposition take- place. Eggs arc shown a little larger than natural at c of figure 1, and much magnified at a and h of figure 2, c showing the sculpture. 1 % larva. — The larva is a soft, whitish, grub-like caterpillar of nearly cylindrical form, with a small, dark head and a few very sparse hairs on each segment. Larvae in the earlier stages of growth arc illus- trated by (I, e, and/ of figure 2. A full-grown larva is shown in profile within an open stem at figure 1. d, and the head and first two thoracic segments appear in figure 2 at g. Mature larvae measure about an inch (25 mm i n length). In the District of Columbia full-grown larvae, as already observed, occur as early as July 1G; in Xew Jersey, later in July, and are to be found upon the vines in different stages in October; at Washington, as late as the second week of November. After attaining maturity the larva' desert the stems and enter the earth, burying themselves to the depth of 1 or 2 inches, and form their cocoons, in which the} transform to pupae. Theoocoon (fig. 1,/) is con- structed of silk and coated externally with fine parti- cles of earth , which adhere < in account of somegummy secretion of the larva. Tht pupa or chrysalis (shown in profile at e, fig. 1 measures about § inch in length (16 mra ). It is shining mahogany brown incolorand its head isorna- mented in front just above and between the eyes with a horn-like process. By means of this the pupa cuts its way out of one end of its cocoon and by the aid of the abdominal hook-like spines forces itself to the surface of the earth before transforming to adult. Number of generations. — The question of the number of generations produced annually in localities of different temperatures which this insect inhabits has been solved by actual observation, the results serv- ing to indicate that it is practically single-brooded on Long Island and northward: that there is a tendency to two broods in Xew Jersey, the moths in exceptional cases completing their transformations late in August or September; that in the latitude of the District of Columbia the species is partially double-brooded, a larger portion of the moths, we may assume, developing as a second generation here than in Xew Jersey; and that in the Gulf States this series is undoubtedly fully two-brooded. [Cir. 38] Fig. 2. — Squash-vine boier*(Melittia satyriniformis): a, Egg as seen from above: //. same from the side, showing sculp- ture; r, sculpt ure of egg, greatly enlarged; head of mature larva from above: o, b, and , , much en- larged: d. e.f. and g, less enlarged (author's illust ration I . I • I : I \ RNTIV1 \ M> 1:1 \i mm \ I MEASUB1 This borer is on exceptionally difficult insect to control, as ordinary insecticides are of no value after the insect has once entered the vines, and repellents are also practically useless. We are, therefore, depend- ent upon cultural methods for relief. Knowing thai the insecl passes the winter in the fields which it has ravaged, it should be superfluous to caution growers against planting squashes in the same ground in successive years. Early squashes as traps. Qood results have been obtained l>\ plant- ing as a trap crop and as eariy a- possible a feu summer squashes, such a- crooknecks and early cymlings, before and between rows "i the main crop of late varieties. The summer squashes attract the insects in such numbers a- t<> leave a smaller number t" deal with upon the late or main crop. As soon a- the earlj crop i- gathered, or earlier if the ground i- needed lor the main crop, the \ inesare promptly raked up and hurtled to destroy all eggs and larva' which they nia\ harbor, and the same treatment i- followed alter gathering the late varieties. This method, according to Dr. J. B. Smith, has proved profitable where used in New Jersey, and should produce good results farther north. Southward, where two well-defined broods appear, it might not be so productive of good, hut it should be given a thorough test. Fall harrowing and deep spring plowing. Experiments conducted hv .Mr. I' - . A. Sirrine. of the New York Agricultural Experiment Station at Geneva, N. Y.. -how that this species can he greatly reduced l>\ lightly harrowing the surface of infested squash fields in the fall so as to bring the cocoons of the vine borer t<> the surface, where they will he exposed to the element-, and then plowing in the spring to a uni- form depth of at lea-t 6 inches, 80 that the adult- will not he able to issue. Other cultural methods. When the vines have attained some length parts of them should be covered over with earth, so that secondary roots will he sent out to support the plant- in case the main root i- injured by the borer. Keeping the plants in good condition, free from other insects and from disease, and well nourished with the assistance of manure or ot her fert ili/.er if necessary, w ill also aid t he plant- to with- stand borer attaek. When vines are 30 badly infested a- to he incapa- ble of bearing fruit they usually die at once, and they should then he promptly taken out and burned. The old vine- should also ho destroyed as soon as the crop is made. Cutting <»it tin borers. The old-time remedy of cutting the borers out of the vine-, although laborious, i- useful, and about the only method open for employment after they have entered the vines. As several individuals often infest a single vine, it i- best to cut longitudi- [Or nally, so as not to sever the vine from the root stalk. If the wound made by cutting be afterwards covered with moist soil it will assist it to heal. The location of the horer in the vine can he readily detected by the accumulation of its yellow 'Trass" or excrement at the point where it is working, and which is kepi open for the extrusion of this matter. i 'apturing /In moths. — This species may he held in partial subjection by keeping a sharp lookout for the parent moths, which are readily seen and not difficult of capture toward dusk or in the cool of the morning, when they are comparatively inactive. The female may then he easily caught, just as she alights on a vine for oviposition." Several persons, including the writer, can vouch for this statement. Summary. — If the grower would make certain of securing a good crop in localities where this and other enemies of the squash occur in their most destructive abundance, it will be necessary for protection against this horer to observe most of the following precautions, and, if possible, secure the cooperation of his neighbors in their observance: (1) Not to plant in or near infested ground. (2) To plant early varieties for the protection of late squashes. (3) To harrow infested fields lightly in fall and plow deeply in spring, to prevent the moths from issuing. (4) To encourage the growth of secondary roots by covering the stems with earth. (5) To destroy dead vines and old plants as soon as the crop is made. (6) To keep the plants in vigorous condition, free from other insects and disease. (7) To cut out such borers as may succeed in entering the vines in spite of the employment of other remedial measures. The capture of the moths before egg deposition is also advisable. Approved : James Wilson, Secretary of Agriculture. Washington, D. C, July 17, 1908. "As additional proof of the practicability of this, the writer refers to the testi- mony of Mr. .]. Y. I). Walker in Insect Life (Vol. IV. pp. L'71. 272 [Cir. 38] o UNIVERSITY OF FLORIDA 3 1262 09216 4515 I