THE HESSIAN-FLY 



133 



27. THE HESSIAN-FLY {Cecidomyia destructor) 



This little fly has long been a deadly enemy to the 

 American farmer. Where it appears in force, wide tracts of 

 wheat and barley become blighted, the stalks bend down, 

 and the ears contain only starved grain. The pest first 

 attracted attention during the American War of Independence, 

 and was popularly believed to have been introduced by the 

 Hessian mercenaries ; hence the name of Hessian-fly. Its 

 native country is still undetermined, and it is not even known 

 for certain whether it originally came from the Old or the 

 New World. Wheat, barley, and rye are the grains which 

 it infests; the timothy-grass of meadows, and 

 the weed known as couch-grass or quick, are 

 also preyed upon; oats seem to escape. The 

 fly chiefly attacks the young plant, but can 

 also subsist on the new growths which push 

 out from plants cut down by the sickle. Since 

 sprouting grain can be found in most countries 

 both in spring and in autumn, the Hessian-fly 

 times its attacks accordingly. There are two 

 broods in the year, and the flies appear just 

 at the seasons when the young plants are ofnfssiairflyfon 

 fittest to nourish the grubs which issue from '^^f of b^rfey, 



, ° magnified. 



the eggs. 



The Hessian-fly is Dipterous, or two-winged, and belongs 

 to the sub-order Nemocera — i.e. with thread-like feelers — 

 which includes the crane-fly, the harlequin-fly, and the gnat. 

 It resembles these insects in the general course of the life- 

 history, as well as in the organisation of the larva and 

 pupa; but the mode of pupation, as will be pointed out 

 shortly, seems to make a transition to the more specialised 

 Diptera, of which the blow-fly is an example — flies which 

 bear plate-and-bristle antenna, and whose larvae are maggots. 



The life-history of the Hessian-fly is shortly this. The 

 eggs are laid upon a young wheat or barley plant. From 

 them issue larvae, which feed upon the sap. When the 

 larva is full-fed, it comes to rest without casting the larval 

 skin, pupates, and then remains dormant for a longer or 

 shorter time, concealed within the food-plant. At last the 



