THE ARMY-WORM. 17 
served. The one shown in fig. 9 inserts a number of eggs 
in the army-worm and the resulting cocoons, which are of 
a white color and surrounded with loosesilk, could be found 
everywhere in the fields fastened to all kinds of plants, to 
sticks and even to loose pieces of sod. The illustration 
shows some of these cocoons fastened to a leaf, a single co- 
coon greatly enlarged, and also the adult parasite, (Apan- 
teles congregatus Say), which leaves the cocoon by a neatly 



Fig. 9.—Apanteles congregatus Say; its cocoons, natural size, and a single 
cocoon with loose cap. Enlarged. Original. 
made circular opening covered by a tight-fitting lid. When 
we dig in the ground after the larger part of the army- 
worms have disappeared, we find, besides the red pupa of the 
army-worm and a large number of dying ones, also numer- 
ous very tough, brown, oblong-oval, silken cocoons from 
which the parasite (Ophion purgatum Say) shown in fig. 10 
issues in due time. When we visit a field invaded by army- 
worms we soon see that the worms have by no means every- 
- ‘sh 
