368 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 



16. The black locust midge. 



Cecidomyia pseudacacice Fitch. 



Order Diptera; family Cecidomyiid.e. 



In July aud August, the tender young leaflets near the tip of the stem folded 

 together like a little pod, the cavity iuside coataining 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, aud then appearing as a small blackish midge. (Fitch.) 



According to Fitcb, before tbe small young leaflets, wbich put fortb 

 along tbe opposite sides of tbe main leaf-stalks at tbeir tips, become 

 expanded, tbey are closed togetber like two leaves of a book ; and it is 

 probably at tbis time tbat tbe female midge inserts ber egg in tbe cleft 

 between tbem, tbe irritation from wbicb and from tbe small maggots 

 wbicb batcb from tbem, keeps tbe leaflet permanei-tly closed; a sligbt 

 cavity forming witbin, in wbicb tbe worms reside, tbe leaflet bereby 

 comes to resemble in its sbape a small bivalve sbell witb a more or less 

 wavy edge. Tbe surface remains uncbanged outside, but witbin it 

 assumes a pale greenisb yellow color. Tbe attacbments of tbe leaflets 

 to tbe stalk becomes so weakened wben infested by tbese worms tbat 

 probably they are generally broken off by the wind, and the worms are 

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

 night, as is tbe habit of tbe wheat midge. 



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

 abdomen pale yellowish, with the tip dusky aud 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 antenna? with thirteen short cylindrical 

 joints separated by short pedicels ; its length, 0.063 inch to the tip of the body. 



17. The YELLOW locust midgk. 



Cecidomyia robinia; Haldemau. 



Order Diptera; family Cecidomyiidjj. 



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 and the wings dusky ; 

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

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



Professor Haldemau, who described tbis two-winged gall-fly in Em- 

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

 in conjunction with tbe Hispa, already mentioned, bad been so numer- 

 ous in southeastern Pennsylvania tbe two preceding summers as to kill 

 tbe 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 tbeir 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 



