TWO LEATHOPPERS INJURIOUS TO APPLE NURSERY STOCK. 7 



field observations it was found tliat this species hibernates in tlie 

 adult stage in woodlands near the nursery at West Chester. The 

 adults become active in the spring about a week earlier than rnalij 

 confining their feeding at first to the foliage of skunk cabbage. 

 From this plant they scatter to grasses and weeds beneath the apple 

 trees in the nursery a few days prior to the first appearance of mall. 

 During the early spring they prefer to feed on any low green vegeta- 

 tion in the nursery row, and never become abundant on the foliage 

 of apple until about mid-season. At this time they appear in num- 

 bers associated with tymU on the terminal leaves. The extent of 

 damage caused by hirdii is small compared with that caused by 

 the common apple leafhopper, and for this reason little attention 

 has been paid to it heretofore. 



Flavescens differs from hirdii by the absence of the characteristic 

 white markings of the pronotum and the smoky bands crossing the 

 elytra. 



This species is allied very closely to hirdii in appearance, and proba- 

 bly in habits and life history, but it is less abundant on the apple. 



JJnicolor is readily separated from mali by the absence of the 



conspicuous white markings of the face and the notum, by its greater 



length and robustness, and by the presence of a pale white spot on 



the middle of the anterior margin of the pronotum and a blue blotch 



on the scutellum. 



, Few field observersations were obtained in regard to the habits of 



unicolor. The nymphs of the first brood were found on apple at 



approximately the same date and about as abundantly as those of 



mali at Hagerstown, Md. The adults of this species do not confine 



their attack to the terminal leaves, being found more frequently on 



the lower part of the trees. This species was taken m scant numbers 



on apple in the vicinity of West Chester and the injury caused by 



it was negligible. 



life history and habits. 



Methods op Study. 



In studying the life history of the two species of apple leafhoppers 

 concerned in this bulletin all data were obtained under outdoor 

 conditions by rearing the insects on young apple stock in the nursery 

 row. Seedlings were planted out early in the spring of 1915 and 

 agam in 1916 on a plot of ground at one end of a few nursery rows. 



Kiley cages and arc-light globe cages (PI. II, A) were used for 

 obtaining records of the length of the egg stage, the extent of repro- 

 duction per female, and the longevity of adults of the different 

 broods. The globe cages were well shaded from the sun by means 

 of large muslin covers over their tops, while ventilation was obtained 

 both from above and below. With the use of such cages practi- 

 cally normal conditions were secured for the rearing of the leafhopper 



