cecidomyid^t:. 11 



these is Ceculomijla {OUgotroplins) destrnctor, commonly call- 

 ed the Hessian Fly, from the belief, probably erroneous, that 

 it was first introduced into this country in straw brought 

 by Hessian troops during the Revolution. 



The fly is very small, but little more than an eighth of an 

 inch in length, of a prevailing black color, with the abdomen 

 pinkish or brownish. There are two broods, in spring and 

 autumn. The female deposits her eggs, one or two at a time, 

 on the upper side of the leaves of wheat, to the number of 

 from eighty to a hundred, or even more. Hatching in from 

 four to eiglit days, if the weather is favorable, the yellowish 

 red larvie crawl downward on the leaves until they insert 

 themselves between the leaf and the stalk. Here they remain 

 quiescent, growing by means of imbibition or absorption of 

 the juices of the plant, until they reach the size of a small 

 grain of rice. The larva?, that are hatched in April in a few 

 weeks assume the pupa state, called the flax-seed stage. In 

 August the second brood appears, the female of which deposits 

 her eggs in young winter wheat or other grain, where the lar- 

 vae soon hatch and acquire the flax-seed condition in a few 

 weeks, or by November, in which condition they pass the 

 winter. In England there is but one brood, that of early 

 summer, and the fly is not nearly so injurious to growing grain. 



TABLE OF GENERA. 



rourtli loiifiitudinal vein wanting-. .... Cecidomvin/i:. 



Fourtli lonjiitudinal vein present. .... Lkstrkmiin.k. 



cecidomyin.t:. 



1. Eiftli lonuitiidina! vein fureate, tlie fir.'it joint of tlie tarsi usually shorter 



than the following. ......... 2 



P'ifth longitudinal vein not furcate, liie metatarsi longer than the follow- 

 ing joint, the la.st two joints very small. .... 14 



2. First and third longitudinal veins distinctly sei)arated from each other 



and from the costa ; costa not tomentose. .... 3 



First and third veins closely appro.\imated to the costa and difficult to 



distinguish, the costa a])])ari'ntly thickened. .... 12 



