THE FALL WEB-WORM. 55 
early in October, and busily engaged in inserting their ovipositors 
through the tough cocoon into their victim within. It seems as if the 
cocoons formed early in the season were on an average a little smaller 
than those formed later. 
“The cocoons of this Apanteles are of a uniform white color, but ex- 
ceptionally a distinctly yellowish cocoon is found. From these yellow 
cocoons nothing has so far been bred; but since, as we have elsewhere 
shown,* the color of the cocoon may vary in the same species, it is 
probable that the variation here referred to is not specific. 
** Not quite one-half of 1 per cent. produced parasites of various kinds. 
“Limneria pallipes Provancher.—In addition to the two Hymenopter-. 
ous parasites treated of, a third one has been very numerous, and has 
done much good in reducing the numbers of caterpillars. This, an Ich- 
neumonid and a much larger insect, does not form an exposed cocoon 
like that of the other parasites described. Yet a little attention will 
soon reveal large numbers of them. Upon the trunks of various trees, 
but chiefly upon those of the poplars and sugar maples, small colonies 
of caterpillars, varying in numbers from four to twelve, could be ob- 
served, which did not show any sign of life. When removed from the 
tree they appeared contracted, all of the same size, and pale or almost 
white. A closer inspection would reveal the fact that the posterior 
portion of the caterpillar had shrunken away to almost nothing, whilst 
the rest was somewhat inflated and covered with an unchanged but 
bleached skin, retaining all the hairs in their normal position. Opening 
one of these inflated skins, a long, cylindrical, brown cocoon would be ex- 
posed; this is the cocoon of the Limneria under consideration. As num- 
bers of such inflated skins would always occur together, it was clearly seen 
that the same parent Limneria had oviposited in allofthem. Most of the 
cocoons were found in depressions of the rough bark or other protected 
places. Single ones were but rarely met with. The Hyphantria larva in 
dying had very securely fastened all its legs into the crevices of the bark, 
so that neither wind or rain could easily dislodge them. Only half-grown 
caterpillars had thus been killed. Many of these inflated skins showed 
‘in the early part of October a large hole of exit in their posterior and 
dorsal ends, from which the ichneumons had escaped. Trying to obtain 
winged specimens of this parasite one hundred and forty of these co- 
coons—and only such as were not perforated in any way—were collected 
and put in a glass jar. Only a single female was produced from all up 
to time of writing, whilst very large numbers of secondary parasites 
issued from October 11 till the 20th of November, and doubtless others 
will appear during the spring of 1887, because some of these inflated 
skins show as yet no holes of exit. 
‘‘ Tachina sp. (Fig. 26).—The parasites of 1. eunea described so far 
all belong to the order Hymenoptera, which furnishes the greatest num- 
*Notes on North American Microgasters, p.7 (author’s edition). 
