312 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



leaves and arranged in masses of from two to five. When the 

 young hatch they bury themselves within the leaf tissue, con- 

 structing a thread-like mine .which they afterwards extend in a 

 curve or semicircle. Transformation to pupae takes place in 

 most cases in loose soil, which the maggots enter to only a short 

 distance, or under fallen leaves. Occasionally maggots trans- 

 form within a leaf if the latter happens to rest on the ground. 

 Dr. Howard states that the eggs hatch in from three to four 



FIG. 262. The beet leaf-miner (Pegomyia vicina Lintn.): a, fly; 6, head of 

 male fly; c, head of female; d, surface of egg highly magnified; e, egg; 

 /, maggot; g, head of same; j, anal segment; k, anal spiracles all 

 enlarged. (After Howard, U. S. Dept. Agr.) 



days, and the larval stage is passed in seven or eight days, the 

 puparium or resting stage requiring from ten to twenty days. 

 " Injury appears to be most frequent in late fall, but 

 even in larger fields such a practice might prevent its increase 

 may be due to earlier generations in midsummer. " In many 

 cases infestation can be traced directly to the insect having 

 bred in lambsquarters and similar weeds, which if not destroyed 

 by ordinary methods of cultivation mature and die during 

 October." 



