10 bisects Injurious to Vegetation. [P^^-f 



are slightly dusky, and fulvous at their insertion into the thorax. 

 Their form and neuration is identical with that of the other spe- 

 cies of this genus, except that the slight connecting nerve between 

 the mediastinal and postcostal is commonly wanting, and the me- 

 dial and forks of the anal nerves are extremely faint for a spe- 

 cies of Cecidomyia so large as this. The legs are pallid-brown, 

 the tarsi black, the femurs paler at their bases. The several pairs 

 of legs equal each other in length, being about 0.24 long when 

 extended, of which length the tarsus embraces one-half. The 

 several joints of the tarsus are of the same relative length as in 

 other species; the short basal joint however, is much more indis- 

 tinct than usual, insomuch that a minute examination of several 

 specimens is required ere one is met with showing this joint dis- 

 tinctly.* This character, and also the neuration of the wings, 

 clearly shows that this species belongs to the genus Cecidomyia, 

 and not to Macquart's genus Lestrimia, nor Meigen's Lasioptera. 



In the male, the antenna', (fig. c^,) are three-fourths of the length 

 of the body, with the joints of a short oval and nearly globular 

 form, the diameter hardly equalling the length: each joint is sur- 

 rounded with a verticil of longish hairs. The terminal joint does 

 not differ from the preceding ones. The two basal joints are com- 

 pacted together as in the female. The antenna diminish very 

 slightly in diameter tow^ards their tips. The fdaments separating 

 the joints are smoky-translucent, nearly as long as the joints, and 

 about one-third of their diameter. The ahdomen (fig. 2,) is cylin- 

 dric or slightly tapering towards its tip, and consists of seven joints 

 beside the terminal one, which (viewed from beneath, vide fig. c,) 

 consists of a transversely oval joint, giving off' two robust process- 

 es, armed with incurved hooks at their tips; and between these 

 processes at their base are two exceedingly minute papillae. As 

 ordinarily seen, in the living specimen, the abdomen is of a brown- 

 ish-black color, more or less widely marked at the sutures with 

 pallid fulvous or smoky whitish lines. In all other points the 

 male coincides with the female in its characters. 



Us duration. — That the fly which comes out in the spring con- 

 tinues but a very short time, I infer from the following data. A 

 number of wheat plants, containing pupae, were transplanted into 

 a box of earth, April 21st, and inspected daily. On the morning 

 of May 1st, about half of them were found to have sent out the 

 perfect fly within the preceding twenty-four hours. On repairing 

 to the field whence these plants were taken, the fly was found to 

 be out in large numbers. At every step, a dozen or more would 



• How well the en2;r.iver has executed hi? task will be obvious by passing 

 a magnifier over the plate. The joints of the tarsi in fig. 3, and other mi- 

 nute details, scarcely, ii' at all perceptible to the naked eye, will then be dis- 

 tinctly recognised. 



