294 Report of the Department of Entomology of the 



mating habits. 



Accounts of the copulatory habits of this species are meagre, 

 but our studies show that the hibernating insects mate while 

 feeding on the raspberry and various plants other than the grape. 

 The first pair in copulation was observed on burdock about ten 

 o'clock on May 20. The weather was fair with a maximum tem- 

 perature for the day of 63° F., and the sun was shining. This 

 appeared to be the beginning of the mating season as the weather 

 previous to this time had been cold and wet, during which timo 

 the insects were sluggish. The next day a copulating pair was 

 observed on a raspberry leaf for about one hour, at about noon. 

 The maximum temperature for the day was 68° F. Mating is 

 accomplished by the male and female bringing the ends of their 

 abdomens together. They remain very quiet except that the 

 claspers of the male are almost continuously active. A slight dis- 

 turbance will cause them to separate. No mating by the over- 

 wintering adults was observed on grape foliage. Many of the 

 males die shortly after copulation as the following facts show: 

 May 20, 225 leaf-hoppers were captured on the raspberry bushes 

 of which 112 were males and 113 females, but during the latter 

 part of May when the migration to the grape was nearly com- 

 pleted the females predominated, there being about one-fourth 

 as many males as females. During the early part of June it was 

 difficult to find males, while the females were numerous. A pair 

 of the summer brood was observed mating on July 23. Unlike 

 the habit of the hibernating forms the act takes place on the grape. 

 The mating season for this brood extended into August. Since 

 this was an unusually cool summer all the dates upon the 

 activities of this insect after July 1 are from one to two weeks 

 later than normal. 



relation of hibernating places to leaf-hopper injury. 



That certain vineyards are more susceptible to attacks by the 

 leaf-hopper is a common observation. The degree of infestation 

 of vineyards is, however, not a matter of chance. Our studies 



