50 



THE REPORT OF THE 



No. 36 



plants. In a large cherry orchard near Beamsville the hoppers were present 

 in myriads, and in walking among the trees one would hear a continual "rustle, 

 rustle, rustle," made by the jumping insects. The leaves in this orchard be- 

 came quite badly mottled as a result of the insects feeding activities. 



Migration to Grapes. About May 21st, or in other words, at the time 

 the third leaf on the grape was showing, the hoppers commenced to migrate to 

 the vineyards. The migratory period extended until about the second week 

 in June; the majority of the hoppers, however, were on the grapes ten days 

 after the migration began. 



Feeding Habits. The leaf-hoppers feed on the under side of the grape 

 leaves — a decided preference being shown for the lower leaves — and by means 

 of their sucking mouthparts withdraw the juices from the plant tissues. As a 

 result of this feeding, the leaves become mottled, and when badly affected, large, 

 brown, dead areas develop on them. This spring the injury caused by the 

 overwintering adults was sufficiently conspicuous to seriously alarm many of 

 the growers. 



Mating. Pairing takes place both on the spring food plants and on the 

 grape. The hoppers copulate frequently and the mating season is extended 

 over a considerable period. 



Grape leaf hoppers x 10. 

 (a) E. comes, (b) E. comes ziczac. (c) E. tricincta. 

 (d) E. vulnerata. 



Mating is accomplished by the male and female bringing the caudal ends 

 of their abdomens together, so that their bodies form a straight line. 



Egg-Laying. By means of her sharp lance-like ovipositor, the female 

 deposits her eggs just beneath the epidermis, almost altogether on the underside 

 of the leaf. 



Owing to the fact that the lower epidermis of the grape leaf on most of our 

 commercial varieties is densely covered with pubescence, the eggs can be located 

 only with the greatest difficulty. For this reason we found that the simplest 

 method of ascertaining the duration of the egg-laying period was to subtract 

 the period of incubation from the dates when the first and last hatched nymphs 

 appeared. * In this way we learned that in the graperies egg-laying commenced 

 about May 24th,* (three to four days after the first adults arrived on the vines), 

 reached its height about June 7th and ceased during the last week of June 

 (June 28th.). 



In the insectary, the egg-laying period of eleven females ranged from 18 to 



*On Ampelopsis eggs laid by E. comes ziczac were first observed on May 9th. 



