108 REPORT 4, UNITED STATES ENTOMOLOGICAL COMMISSION. 
the winter in both the pupa and fly states. From the known prefer- 
ence of this fly for decaying or putrescent flesh, it is probable that the 
female is attracted more to diseased or injured chrysalides than to vig- 
orous worms. 
Another species (Gyrtoneura stabulans Fallen, Fig. 37), the habits of 
which are rather predaceous than parasitic, was figured and described, 
but not identified, in the Department Report on Cotton Insects. We 
may appropriately consider it here, though it really preys upon the 
chrysalis. Seven larvae emerged from eggs which, had been deposited 
upon the leaves surrounding Aletia pupae, and reached full growth in 
ten days, having meantime devoured six Aletia pupae. They then en- 
tered the ground and remained in the pupa state five days. 
We have also obtained this fly from Aletia chrysalides, and quote 
the following passages from the American Naturalist (September, 1882, 
p. 740), as bearing on the ques- 
tion whether it is a parasite 
or a scavenger: 
Is Cyrtoneura a Parasite ok 
Scavenger? — Last spring wo scut 
specimens of a Muscid for determi- 
nation to Mr. R. H. Meade, Brad- 
ford, England, and he kindly wrote 
us as follows regarding this species 
which was bred from chrysalides of 
the Cotton Worm : 
"The Dipterous insects which I 
received yesterday are one male and 
two females of Cyrtoneura stabulans (After Coms'tock.) 
Fallen. This fly is common through- 
out Europe, and also occurs in North America, according to Loew and Walker (see 
Osten Sacken's Cat. of Dipt, of N. A., edit. 2d, p. 163). The larvos usually feed upon 
decaying vegetable substances, as fungi, &c, but Schiner (Fauna Austriaca, Dipt., 
Vol. 1, p. 597) says, according to Bremi and Hartig, they also live upon the larvae of 
Lepidoptera and bees. It is a very interesting fact that they also eat the Cotton- 
worms. Your American specimens seem to be perfectly identical with my British 
ones, but are rather smaller. I may add that the genus Cyrtoneura Macq. belongs 
to the family of the true Muscidse."* 
There can be no doubt that the Cyrtoneuras we bred issued from pupoB of Aletia, 
but as the usual habits of the species are those of a scavenger, some doubt has arisen 
in our mind as to whether it is a true parasite. Wo recall to our readers another 
dipterous insect, the Phora aletiw Comstock, which has been called, by its describer, 
one of the most important parasites of the Cotton-worm, and which nevertheless 
turns out to be a mere, scavenger. Cyrtoneura stabulans may, like this Phora, lay her 
eggs on the decaying pupae of Aletia, which are so commonly met with at the time 
tin; worms have defoliated the fields and have also eaten the leaves which sheltered 
the chrysalides. These chrysalides w hen exposed to the light and heat of the sun 
are very Liable to rot, and on examining tin; chrysalides hanging on the defoliated 
plants, by far the larger portion of them will be found to be rotten, many containing 
Fig. 37. — Cyrtoneura stabulans : a, e,gg (natural .size); b, 
egg (enlarged) ; c, larva (enlarged) ; d, head and first thor- 
acic segment of larva, still more highly magnified ; c, 
puparium ; /, adult, natural size indicated by hair lines. 
See also Mr. Meade's note on the same subject in the (London) Entomoloyist, June, 1882, pp. 
140-141. 
