466 INSECTS INJURIOUS TO VEGETATION. 



erated," she adds, " hundreds with my penknife, and thousands 

 make their escape after the grain has been reaped and carried 

 into the barn. When the insect is thus unnaturally retarded, 

 the time of its perfect development is uncertain ;" and she has 

 "found them on the straw, and in spiders' webs, from June 

 until September." Four of the specimens sent to me by Miss 

 Morris were males. Another subsequently received was a 

 female. The former were not more than half the size of the 

 latter, and indeed were smaller even than the wheat-fly, which 

 they seemed somewhat to resemble. The female was evi- 

 dently much darker colored originally than the males. These 

 insects were genuine specimens of Cecidomi/ia, and apparently 

 of a different species from the Hessian fly. The condition of 

 the specimens, which had suffered by compression and by being 

 badly preserved, was such that an accurate comparison and 

 description of them could not be made. I understand that 

 the species has disappeared from Germantown and the vicinity, 

 and hence no opportunity for obtaining living or recent speci- 

 mens has occurred since the year 1843. 



Various means have been recommended for preventing or 

 lessening the ravages of the Hessian fly; but they have hith- 

 erto failed, either because they have not been adapted to the 

 end in view, or because they have not been universally adopted; 

 and it appears doubtful, whether any of them will ever entirely 

 exterminate the insect. It is stated in the before mentioned 

 Report of " The Philosophical Society," that Miss Morris ad- 

 vises obtaining "fresh seed from localities in which the fly has 

 not made its appearance," and that " by this means the crop 

 of the following year will be uninjured; but in order to avoid 

 the introduction of straggling insects of the kind from adja- 

 cent fields, it is requisite that a whole neighborhood should 

 persevere in this precaution for two or more years in succes- 

 sion." "This result," Miss Morris says, "was obtained, in 

 part, in the course of trials made by Mr. Kirk, of Buck's 

 county, Pennsylvania, with some seed-wheat from the Medi- 

 terranean, in and since the year 1837. His first crop was free 

 from the fly; but it was gradually introduced from adjacent 

 fields, and, in the present year (1840), the mischief has been 



