51 



sparse!}' covered with long stiif black hairs. When in action the 

 body is carried usuall^y in a somewhat curved position, but when 

 extended measures nearly a quarter of an inch. The maggot {f) is 

 white, and so nearly transparent that the contents of the abdomen can 

 be seen through the posterior portion. 



In many cases infestation can be traced directly to the insects hav- 

 ing bred in lambs-quarters and similar weeds, which if not destroyed 

 by ordinary methods of cultivation mature and die during October. 

 The flies, b}" close observation, may be seen in flight just above the 

 ground or hovering about their different food plants. The eggs 

 are placed on the lower surface of the leaves and arranged in masses 

 of from two to five. When the young hatch the}" bury themselves 



Fig. 50. — Pegomya vicina: a, fly; 6, head of male fly; c, head of female; d, surface of egg, highly mag- 

 nified; €, egg; /, maggot; r/, head of same; h, cephalic hooks of maggot; i, prothoraeic spiracles; 

 j, anal segment; k, analspiracles; I, imparium — all enlarged (after Howard, Division of Entomology). 



within the leaf tissue, constructing a thread-like mine which they after- 

 wards extend in a curve or semicircle. 



Transformation to pupa3 takes place in most cases in loose soil, 

 which the maggots enter- only to a short distance or under fallen leaves. 

 Occasionally maggots transform within a leaf if the latter happens to 

 rest on the ground. 



Injury appears to be most frequent in late fall, but may be due to 

 earlier generations in midsummer. Dr. Howard states that eggs 

 hatch in from three to four days, and the larval stage is passed in seven 

 or eight days, the puparium or resting- stage requiring from ten to 

 twenty days. These periods will vary according to the state of the 

 atmosphere. An instance of damage to spinach in Pennsylvania was 

 reported in May, 1903. 



