INJURIOUS INSECTS. 233 



j spare its luxuriant burthen and not be poorer, and the land is im- 

 proved by the amount of the manure, a luxuriant sod being as it 

 were its representative. 



Such, in my view, is a practical way of increasing the effects of 

 manure, and securing for the earth a store of vegetable food derived 

 from the atmosphere. 



INSECTS INJURIOUS TO VEGETATION.— No. 3. 



BY ASA FITCH, M. D. 



THE WHEAT-FLY. 

 Although several facts in the habits and economy of the wheat-fly 

 had occurred to my notice at sundry times since its appearance in 

 this vicinity, yet as my leisure for studies of this nature was wholly 

 engrossed in other departments of the science of entomology, these 

 facts had been observed in too cursory a manner to be of material 

 value in preparing an account for the public eye. It has not been 

 until the present year, that I have made this and iis allied species 

 my particular study. And as some few interesting points still remain 

 jndetermined, ere a perfectly complete history of this insect can be 

 given, I should be inclined still to defer preparing a paper upon this 

 5ubject, but that I deem some of the observations already made of 

 -00 much importance to be longer withheld, and am moreover very 

 .veil aware. that if no writer ventured to appear before the public 

 jntil his investigations were so complete in every particular that he 

 :ould exhaust the subject on which he wrote, very little would be 

 published, and the world would have but a small fraction of that 

 imount of information which it now possesses. 



It is necessary for me farther to premise, that although we have 

 wo distinct species of wheat-flies, as will be fully shown in the 

 sequel of this paper, to wit, the clear-winged wheat-Jly (Cecidomyia 

 ritici of Kirhy) and the spotted-winged ivheat-Jly, which has hither- 

 remained a nondescript ; yet as nothing is yet known of the 

 labits and transformations of one of these as distinct from the other, 

 hrough the body of this article the copimon name "wheat-fly" will 

 )e employed for convenience as referring to both these species. 



