368 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 



16. The black locust midge. 



Cecidomyia pseudacacice Fitch. 



Order Diptera ; faraiJy Cecidomyiid.e. 



lu July and August, the tender young leaflets near the tip of the stem folded 

 together like a little pod, the cavity iuside containing from one to three small milk- 

 white maggots, which descend below the surface of the ground, remaining there in the 

 pupa state about ten days, and then appearing as a small blackish midge. (Fitch.) 



According to Fitch, before the small young leaflets, which put forth 

 along the opposite sides of the main leaf-stalks at their tips, become 

 expanded, they are closed together like two leaves of a book ; and it is 

 probably at this time that the female midge inserts her egg in the cleft 

 between them, the irritation from which and from the small maggots 

 which hatch from them, keeps the leaflet perraauertly closed; a slight 

 cavity forming within, in which the worms reside, the leaflet hereby 

 comes to resemble in its shape a small bivalve shell with a more or less 

 wavy edge. The surface remains unchanged outside, but within it 

 assumes a pale greenish yellow color. The attachments of the leaflets 

 to the stalk becomes so weakened when infested by these worms that 

 probably they are generally broken ofl" by the wind, and the worms are 

 thus carried to the ground, instead of crawling down the stalks by 

 night, as is the habit of the wheat midge. 



The female. — A small blackish midge, the base of its thorax tawny yellow, its 

 abdomen pale yellowish, with the tip dusky and clothed with fine hairs, as is also 

 the neck; its legs black, with the thighs pale except at their tips; its wings dusky, 

 feebly hyaline, with the fringe short; its antennai with thirteen short cylindrical 

 joints separated by short pedicels ; its length, 0.065 inch to the tip of the body. 



17. The yellow locust midge. 



Cecidomyia robinicv Haldemau. 



Order Diptera; family Cecidomyiid.e. 



In July and August a portion of the edges of the leaves rolled inwards on their 

 under sides and thickened, inclosing one or two very small white maggots, which 

 are varied more or less with orange-yellow ; producing a pale orange midge with the 

 sides of its thorax and often three oval stripes on the back aud the wings dusky ; 

 its antennte blackish and of fourteen joints in the females, twenty-four in the males; 

 its length, 0.12 inch. (Fitch and Haldeman.) 



Professor Haldeman, who described this two-winged gall-fly in Em- 

 mon's Journal of Agriculture and Science, October, 1847, says that it 

 in conjunction with the Hispa, already mentioned, had been so numer- 

 ous in southeastern Pennsylvania the two preceding summers as to kill 

 the leaves upon the locusts, the trees in August appearing as though 

 they had been destroyed by dry weather. 



This insect may be detected by the margin of the leaflets being rolled 

 inwards upon their under sides for a length varying from over a quar- 

 ter to a half inch, the upper side showing a concavity or rounded hollow 

 at this point. "This rolled portion," says Fitch, "is changed in its 



