INSECTS INFESTING WHEAT. 



277 



Fig. 263.--At the left, a Fig- 263. 



liealthy wheat plant ; at the 

 right, a plant infested hy the 

 maggots or larva' of the Hes- 

 sian fly. 



The transformation of this 

 species is different from some 

 others in the pupa or chrys- 

 alis state, inasmuch as it first 

 passes through what is termed 

 hy naturalists the "flax-seed" 

 state. It assumes the pupa 

 form only a few days before 

 the perfect insect emerges. 



This pest produces two 

 l)roods each year — one in the 

 Spring and one in Autunni. 



The perfect insect (Fig. 259) 

 is described as follows : "Col- 

 or, black, except that the alj- 

 domen is more or less tawny, 



each ring being marked iwovq. or less with l)lack ; legs, pale-red 

 or brownish, with black feet; wings, three-veined, ciliate or 

 fringed. The length of the insect is aljout one tenth of an 

 inch, the expansion nearly one quarter of an inch." The 

 insect belongs to the order ch'ptcra, or two-winged flies. 



Dr. Cyrus Thomas, State Entomologist of Illinois, writes as 

 follows : 



"does the HESSIAN FLY EMIGRATE? 



" As regards the so-called emigration of this insect, we would 

 express our disbelief in any such movement from place to 

 place as is involved in tlie idea of the word cmif/ration. The 

 history of the insect simply shows that it has steadily spread 

 from its original point of introduction to new sections of the 

 country as rapidly as they were settled and wheat became a 

 staple article of production. 



" It is jjeriodically a])un.dant ; most other noxious insects 

 are more aljundant some years than others, becoming abun- 



