INSECTS INJURIOUS TO BEANS AND PEAS 



107 



than the onion maggot, measuring about one- fourth of an 

 inch. 



This fly is evidently of European origin, and was first rec- 

 ognized in New York State in 1856. Like so many other flies, 

 it ranges through several life areas, and we know of its occur- 

 rence in New England, Canada and Minnesota, southward to 

 the Gulf, and westward to the Pacific. 



Injury is most severe to young plants, and particularly to 

 beans, peas, and Indian corn. Cabbage, turnip, radish, beets, 

 9 d 



Fig. 63.— Seed-corn maggot a. Male fly; c, head of female; d, larva, from side; 

 e, anal segment of larva; /, anal spiracles; g, thoracic spiracles; h, puparium. 

 All much enlarged. (Author's illustration, U. S. Dept. Agr.) 



onion, seed potato and hedge mustard are also attacked, and the 

 maggots even feed on the eggs of grasshoppers. The insect 

 apparently breeds on decaying vegetable and perhaps animal 

 matter of various kinds. A single generation only develops in 

 corn, but later ones might be produced on bean and pea, owing 

 to the longer period in which these crops are grown. The flies 

 are found southward throughout the year, but in the north there 

 must be a period in midwinter in which breeding ceases; per- 

 haps also another in midsummer. 



