THE FALL WEB-WORM. 51 
death of avictim. In some places, and notably upon the trunks of pop- 
lars, these cocoons were so numerous as to attract attention; it seemed 
as if the trunk had been sprinkled with whitewash. But notwithstand- 
ing such vast numbers, but two specimens of the architects of these neat 
cocoons were raised; all the rest had been parasitized by secondary 
parasites.* It is barely possible, however, that some specimens may 
hibernate in their cocoons, since numbers of them have as yet (Decem- 
ber 20, 1886) not revealed any insects. The winged Apanteles leaves 
the cocoon by a perfectly round orifice in the front, by cutting off a little 
lid, which falls to the ground. Its parasites, however, leave by small 
holes cut through the sides. These secondary parasites were very com- 
mon late in September and early in October, and busily engaged in in- 
serting 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 excep- 
tionally a distinctly yellowish cocoon is found. From these yellow 
cocoons nothing has so far been bred, but since, as we have elsewhere 
shown,t 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 Ichneu. 
monid 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 observed, 
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 exposed; this 
is the cocoon of the Limneria under consideration. As numbers of such 
inflated skins would always occur together, it was clearly seen that the 
Same parent Limneria had oviposited in all of them. 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 nor rain could easily dislodge them. Only half-grown 
caterpillars had thus been killed. Many of these inflated skins showed 
* There are a number of these secondary parasites, but as they are still issuing we 
shall not treat of them in detail in the present article. 
t Notes on North American Microgasters, p. 7 (author’s edition). 
