THE FALL WEB-WORM. 49 _ 
moth, and the larve produced soon consume the contents. This egg- 
parasite is a very useful friend, nipping the evil in the bud, so to speak. 
Meteorus hyphaxtria, Ri- 
ley. —“ This parasite (Fig. 
24) has performed very 
good services during the 
caterpillar plague, and has 
done much to check any 
furtherincrease of the Web- 
worm. During the earlier 
part of the summer this in- 
sect was not very nume- 
rous, but sufficient proofs 
in the form of empty co- 
coons were observed to in- 
dicate at least one earlier 
brood. Towards theend of 
September, and as late as Fic. 24.—Meteorus hgphantrie: a, female; 6, cocoon (en- 
the 15th of October, very dareed) 
numerous cocoons of a second brood were formed ; they could be found 
in all situations to which the caterpillar itself had access. But the 
great majority of them were suspended from the trunks and branches 
of trees, and chiefly from near the base of the trunk. Hach cocoon rep- 
resents the death of one nearly full-grown caterpillar, since the latter 
harbors but one larva of the parasite.* A careful watch was kept to 
see how such a suspended cocoon was formed, but in vain. Once a larva 
had just started to make a cocoon, but it was prevented from finishing 
it by a secondary parasite, and it died. Another larva had already spun 
the rough outside cocoon, but became detached and dropped out of the 
lower orifice, and commenced a new one. The larva, suspended by the 
mandibles, evidently spins at first loose, irregular, horizontal loops 
around its body, until a loose cradle is formed. The silk secreted for this 
purpose hardens very rapidly when exposed to the air. When secure 
inside this cradle it lets go its hold with the mandibles, and finishes the 
soft inside cocoon in theusual manner. If the larva has dropped to the 
ground it still makes an outer loose cocoon, but the silken threads are 
thicker and much more irregular. In cocoons made during a high wind 
the threads that suspend them are much longer, reaching sometimes the 
length of 4 inches; the more normal length varies from 13 to 2 inches. 
“To find out the length of time which this insect occupies in matur- 
ing inside the cocoon, 44 freshly-made cocoons were put in a glass 
jar. With a remarkable regularity but ten days were consumed by the 
insect in changing from the larval to the winged form. The winged 
Meteorus issues through a perfectly round hole at the lower end of the 
*In only one instance the cocoon of this parasite was found inside that of its host. 
17527—Bull. 10 4 
