102 INSECTS INJURIOUS TO FOREST AND SHADE TREES. 
ably 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 the habit of the wheat midge. 
The female.—A small blackish midge, the base of its thorax tawny yellow, its abdo- 
men 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 hya- 
line, with the fringe short; its antennze with thirteen short cylindrical joints sepa- 
rated by short pedicels; its length 0.065 inch to the tip of the body. 
11. THE YELLOW LOCUST MIDGE. 
Cecidomyia robinie Haldeman. 
Order DipTERA; family CECIDOMYIAD A. 
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 antennie 
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- 
mows Journal of Agriculture and Science, October, 1847, says that it, 
in conjunction with the Hispa already mentioned, had been so numerous 
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 quarter 
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 color to 
a paler yellowish green, and its texture is thickened and succulent.” 
The same leaf sometimes has two or more of these folds along different 
parts of its margin. 
The larva is colorless or watery when young, becoming, as it approaches maturity, 
opaque and milk white, varied more or less with bright yellow. It is long oval, 
broadest in the middle and tapering thence to a sharp point anteriorly, the opposite 
end being bluntly rounded, and is divided into thirteen segments by transverse im- 
pressed lines. (Haldeman.) 
12. THE LOCUST SAW-FLY. 
Nematus similaris Norton. 
Order HYMENOPTERA; family TENTHR EDINID®. 
Eating the leaves of the black locust, a small, soft, green worm + inch long, with 
20 legs, and a brownish head; appearing in Washington, D. C., late in August until 
October; transforming in a dark-brown oval cocoon, and two or three weeks later 
issuing as a saw-fly nearly 4 inch long, of a dirty yellow color, with a squarish black 
patch on top of the head, the sides and front of the thorax black, and a transverse 
band on top of each abdominal segment. (Comstock. ) 
This saw-fly inserts its irregularly semi-ellipsoid eggs in a crescent- 
haped cut made in the under surface of the leaf by the “saw.” In a 
