202 



of joints is not constant, and that at any rate this character 

 ought not to be depended on for discriminating the species. 



I cannot reply just now to your questions respecting the color 

 of the abdomen in the $ . According to my recollection the 

 color is due chiefly to the mass of eggs within, and varies much 

 in different individuals, and so does the hairy clothing of the 

 abdomen. 



HAREIS TO HERRICK. 



Cambridge, Sept. 20, 1852. 



I am sorry you could not send me specimens of Say's Cera- 

 fhon\ those received from Dr. Fitch differ somewhat in color 

 from Say's description ; — but if otherwise the same cannot be- 

 long to Eurytoma. My article is partly in print already, and 

 cannot be materially altered now. I have thought best to re- 

 tain Mr. Tighlman's statement because it is so full and circum- 

 stantial, and withal of an early date. I have seen the Hessian 

 Fly in the flaxseed state, and have raised therefrom specimens of 

 the fly, and so far, can speak from personal observation. I have 

 also several other species of Cecidomyia^ several of which have 

 been raised from the larvae. Including the Hessian Fly, there 

 are now four species, Avith whose history and transformations I 

 have become acquainted from personal observation. These are 

 C. destructor^ C. salicis, C. tritici and C. rohinice. All of these 

 agree essentially in their characters in the winged state. There 

 is no genus, except Ceeidomyia^ to which I can satisfactorily re- 

 fer them ; and I am at a loss to know what the characters of 

 Cecidomyia are, if not such as are found in these insects. In 

 that section of LasiojJtera which has the first tarsal joint short, 

 the antennas are not surrounded with whorls of hairs, one of 

 the essential characters of Cecidomyia. On revising your valu- 



