590 DIPTEEA. 



oval form, tapering at each end. The pupae found in the 

 ears were very few in number, scarcely one to fifty of the 

 maggots. Hence Mr. Kirby supposes that the latter are 

 not ordinarily transformed to flies before the spring. To- 

 wards the end of September he carefully took off the skin 

 of one of them, and found that the insect within still retained 

 the maggot form, and conjectures that the pupa is not usu- 

 ally complete until the following spring. 



It is evident, from these observations, that the English 

 naturalists above named regarded the insect as having en- 

 tered upon the pupa state when it ceased feeding and became 

 quiescent, at which time Mr. Kirby found it generally to 

 adhere somewhat to the grain. In applying to it, in this 

 condition, the name of chrysalis or pupa, and describing it as 

 such before it exhibited- any trace of " the lineaments of the 

 future fly," and while " still in the form of the larva," they 

 'followed the common usage of naturalists, as stated in my 

 account of the Hessian, fly. They cannot, therefore, be 

 said to have mistaken the larva for the matured pupa ; the 

 remarks of Mr. Kirby prove that he was well aware of the 

 difference between them. Mr. Kirby, however, was mis- 

 taken in his conjecture that " the insect enclosed itself in a 

 thin membrane to protect itself from the cold of the win- 

 ter " ; the membrane referred to being merely the outer skin 

 of the larva, loosened previously to being cast off entirely, — 

 a process which he did not observe. 



According to Mr. Gorrie, the maggots quit the ears of the 

 wheat by the first of August, descend to the ground, and 

 go into it to the depth of half an inch. That they remain 

 here unchanged through the winter, and finish their trans- 

 formations, and come out of the ground in the winged form, 

 in the spring, when the wheat is about to blossom, is ren- 

 dered probable from the great number of the flies found by 

 Mr. Shirreff, in the month of June, in all the fields where 

 wheat had been raised the year before. The increase of 

 these flies is somewhat checked by the attacks of three 



