708 REPORT UNITED STATES GEOLOGICAL SURVEY. 



thread-like lines ; while the upper part is dark, with an interrupted white thread 

 runuing exactly through the middle of the back. The prolegs, ten in number, are 



marked on their outer middle and 

 on their tip w.ith black. Beneath, 

 the caterpillar is of a livid green. 



Jlost of the Maine species of Leii- 

 eania have light-colored wings, with 

 dark streaks and dots, but the uni- 

 piiHcta is larger and darker colored. 

 Its prevailing hues are rusty gray- 

 ish-brown, sprinkled or peppered 

 sparsely with black scales. The 

 upper part of the head, the front 

 part of the thorax or collar, and 

 front margin of the fore wing, are of 

 Fig. 7.— a, male moth; b, abdomen of female— natur.-il size; a lighter shade. Between the front 

 c. eye; rf, base of male autennie; c. base of female antenna; niargia of the fore win"" and the 

 enlarged.— (After Eiley.) vein, or raised line reaching out to 



the white spot in the center, is a rusty patch. Just beyond, about half-way between 

 the white dot and the outer edge, is a row of about ten black dots, situated on the veins, 

 running toward the apex of the wing, but the last three are deliected at a right angle 

 inward and up to the front margin, while a dark line starts from the corner or curve 

 in the line of dots, and proceeds to the upjier angle or apex of the wing. The little 

 ■veins of the outer edge are silvery, and between them, in a row next to the fringe, can 

 just be seen little black dots. 



The hind wings are pearly smoke-colored, darker toward the outer edge, with a 

 central sjiot of the same color, which can be seen on the under side. 



Beneath, the moth is a light pearly-gray. The fore wings are clouded in the middle, 

 with a dark spot on the front margin, one-fourth of the way from the tip. The fore 

 wings are rather more pointed in this species than the other. The body measures 

 nearly an inch long, and the wings exx^and a little over an inch and one-half. 



Summary. — The army-worm moth appears late in the summer or early 

 ill the autumn, wheu it hybernates, after laying its eggs near the roots 

 of perennial grasses ; or it hybernates in the chrysalis state and ovi- 

 posits in April and May southward ; later, northward. The eggs hatch 

 and the young appear eight or ten days after, and the worms are most 

 destructive in wet summer succeeding a dry one, when the " wheat is iu 

 the milk," The caterpillar state took a month ; the chrysalis state two 

 weeks. The species is mostly confined to the Middle and Xorthern 

 States. Besides external enemies it has eight internal parasites. The 

 best way to exterminate the worm is to burn meadows and grass-lauds, 

 where the insect lays its eggs, in the autumn. 



European Wheat-Flies. — Several very destructive flies are known 

 in Europe to injure the stalks and leaves of wheat and other cereals, 

 and as they are liable to be imported into this country, I will refer to 

 them. The Oscinis granarms in England lives in the stalks of wheat; 

 Oscinis vastator iu Europe damages wheat and barley by eating the base 

 of the stalk. The larva becomes fully grown late in June, and a month 

 later the fly appears. It is said to be attacked by numerous Pteroma- 

 lus parasites, and a minute Prototriipid ichneumon oviposits in its eggs. 

 Allied s])ecies causes the disease called "gout," producing swellings 

 twice the size of the stulks of wheat and barley. Oscinis frit affects 

 the ears of barley, in certain years destroying one-tenth of the entire 

 crop. Two si)ecies of another genus {Chlorops) are especially injurious 

 in Euroi)e. Chlorops lincata destro^-s the central leaves and the plant 

 itself, the female ovipositing on stems when the wheat begins to show 

 the ear. In two weeks the eggs hatch and the fly appears in September. 

 Chlorops hcrpinii attacks the ears of barley, from six to ten larvie being 

 found in the ears, destroying the flowers and renderhig them sterile. 

 In dealing with these insects plowing in has been found to be of no 

 use, and the best preventive measure is the rotation of crops. 



