836 
ANNUAL REPORT OP NEW YORK 
LOCUST. LEAVES. 
which this worm feeds. This being consumed from the mid-vein to the 
outer margin, the thin membrane of the under surface of the leaf which is 
hereby separated, loses its vitality and ceases to grow ; whilst the upper 
layer of parenchyma, being uninjured, continues to expand. But the dead 
membrane on its under side holds it, like a bridle, from expanding further 
outwards, and it hence bulges upward, convexly. Thus the cavity in the 
leaf assumes the shape of an oven, ite floor flat and its roof arched or con¬ 
cave. Thus ample room is furnished for the cocoon to be suspended, like 
a hammock, in the centre of the cavity. 
Frequently, instead of the cavity in the leaf being occupied with a few 
fine threads supporting a cocoon in the centre, we meet with one or two 
smaller and much narrower snow-white cocoons, promiscuously placed. 
They are 0.12 long and a fourth as broad. In due time the ends of these 
cocoons are raised, like a lid, and a minute parasitic fly comes from them, 
the larva of which have subsisted upon and destroyed the larva of this 
leaf miner. It pertains to the family Braconidce, and the genus Micro- 
gaster, and may be called 
The Locust leap-miner parasite, Microgaster Rolinire. — It is 
cream yellow or straw yellow, with the antenna; and legs pure white, the 
female being deeper yellow or orange, with the tip of the abdomen often 
dusky. Its wings are pellucid whitish, with colorless veins, the small cen¬ 
tral cellule being open on its hind side. The male is 0.07 long, and to the 
tip of its wings 0.11, its antennae being 0.10. 
335. Slender locust leaf-miner, Argyromigei PseudacacielUi, new species. (Lepi- 
doptera. Yponoineutidue.) 
In similar white blister-like spots, a much more slender worm, not flat¬ 
tened, very deeply constricted at the sutures and resembling a string of 
beads; producing a minute moth only 0.24 in width, its fore wings golden 
yellow with four white bands on their outer side, the forward ones oblique, 
broader and edged with black lines, and also three or four similar white 
bands on their inner side and a large black dot on their tip half encircled 
with whitish. 
This larva occurs in the blister-like spots of locust leaves at the same 
time as the preceding, but is at once distinguished from it by its more 
slender form, very little tapering from before backwards, and not at all 
flattened. Its legs are also much larger and more distinct, showing three 
pairs anteriorly, three on the middle abdominal segments and one pair at 
the tip. A few soft hairs are scattered over its body. Its head is small 
and is sometimes wholly retracted within the neck. It is divided into 
twelve rings by very wide deep constrictions, giving to the worm a striking 
resemblance to a string of very small beads, usually of a watery whitish 
color with a brown line along the middle, but sometimes curiously diver¬ 
sified from internal alimentary substances in different stages of digestion. 
Thus a worm was in one instance noticed as having the threo first rings 
