214 HALF HOUES WITH ESTSECTS. [Packard. 



pupa-case in which it has been wrapped like a mummy. 

 This occurs just as the wheat is coming up. For a period 

 extending over three weeks they lay their eggs and then 

 disappear. The maggots hatched by the eggs laid by the 

 spring brood assume the flax-seed form in June and July, 

 and are found unchanged in the autumn, most of them re- 

 maining in the stubble. This is a most important fact, of 

 which the farmer may take advantage. Now, if the stubble 

 be burned in the autumn, millions of these maggots will be 

 destroyed, and if this process were carried on in every wheat 

 field in the country the ravages of this and other destructive 

 insects would be stayed. As it is now we are almost wholly 



Fig. 168. 



Parasite of Hessian Fly. 



dependent on nature's means of preventing their too great 

 increase. Figure 168 shows (much enlarged) a parasitic 

 four-winged Chalcid fly, which has the instinct to thrust its 

 ovipositor through the sheath of the leaf under which the 

 maggot of the Hessian fly lurks, and deposit an egg in its 

 body. Dr. Fitch has suggested that the European parasite 

 of this and the wheat midge should be imported and bred 

 by the quantity, so as to stop their ravages. It would be a 

 simple thing to do. A quantity of stubble from an English 

 or French wheat field could be imported and scattered over 

 the wheat fields of southern New England and the Middle 



22 



