﻿12 BULLETIN 19, U. S. DEPARTMENT OF AGRICULTURE. 



Ohio, in the spring of 1912 produced a brood of nymphs which 

 matured to adults. These adults, in turn, produced nymphs which 

 developed to adults of the second summer brood. Observations in 

 the vineyards of Ohio and Michigan, however, during August of 1911 

 and of 1912 indicate that this species produced a much smaller 

 number of second-brood nymphs than did T. comes in the vineyards 

 surrounding North East, Pa. 



It should be added that a very large percentage of the grapevines 

 grown in the Michigan vineyards are of the Concord variety, and 

 that on these vines T. tricincta is the predominating species, whereas 

 in the vineyards of the Chautauqua and Erie grape belt, where the 

 Concord is the leading variety grown, T. comes is the predominant 

 and destructive species. 



Little, if any, effort has been made thus far by the vineyardists of 

 Michigan to control T. tricincta, although in the season of 1911 it 

 was quite destructive in many vineyards. Several vineyardists in 

 the vicinity of Lawton and Paw Paw were planning to combat it 

 with a tobacco-extract spray in 1912, but although there was a 

 heavy infestation of overwintering adults in the spring these failed 

 to produce a large enough brood of nymphs to injure the vines seri- 

 ously, thus rendering a spray treatment unnecessary. 



DESCRIPTION. 



THE ADULT OR WINGED FORM. 



The adult grape leaf hopper (Typhlocyba comes Say) (see fig. 1, 

 p. 1) is an insect about one-eighth of an inch long. The original 

 description of the insect by Say, made in 1825 (see Bibliography), 

 is as follows: 



Pale yellowish with sanguineous spots. Inhabits Missouri. 



Body pale yellowish; head, a transverse sanguineous line, profoundly arcuated 

 in the middle, and a smaller transverse spot before; eyes fuscous; thorax with three 

 sanguineous spots, the lateral ones smaller and the intermediate one arcuated; scutel, 

 a sanguineous spot at tip; hemelytra yellowish white spotted with sanguineous; spots 

 arranged two at base, of which the outer one is small and the inner one elongated 

 and abruptly dilated on the inner side at tip; two upon the middle, of which the 

 outer one is elongated in a very oblique line; the two behind the middle, of which 

 the inner one is obliquely elongated, and the outer one smaller and interrupted; and 

 a transverse linear one near the tip, ramose upon the nervures; feet whitish. 



Length to the tip of the hemelytra one-ninth of an inch. 



The line and spot on the head and the spots of the thorax are sometimes obsolete, 

 but are always visible, and the latter are sometimes connected by curving toward 

 the anterior edge of the thorax. The spots of the hemelytra are also sometimes 

 slightly interrupted, or connected into four oblique bands. 



In winter the color markings are deep salmon-red. After the 

 insects have fed upon the foliage of the grapevine for a short time 

 the color becomes paler and is displaced by a light yellow. In the 



