6 
BULLETIN 204, U. S. DEPARTMENT OF AGRICULTURE. 
A brood of this species develops under favorable weather conditions 
in about four weeks. The first brood appears in August and the 
insect continues to breed until cold weather sets in. Owing to the 
fact that several broods develop in a single season, the insect increases 
very rapidly. It can be reared in the laboratory for the purpose of 
colonization, and this work is being done each year. Unfortunately 
the insect does not always survive the winter in good condition, so 
that its occurrence in the colonies where it is liberated is by no means 
as uniform as that of Anastatus, 
Apanteles lacteicolor Vier. (fig. 3) is a small hymenopterous parasite 
which deposits its eggs in the small caterpillars of the brown-tail 
moth in August. The eggs of the parasite hatch in the body of the 
small caterpillar, but development is very slow during the fall. 
Caterpillars that are attacked in 
this way feed and enter the hiber- 
nating web with their more for- 
tunate comrades. They pass the 
winter and emerge with the others 
early in the spring. As soon as 
they have become active and 
begin feeding the Apanteles larva 
also begins feeding and by the 
time the caterpillar is about one- 
fourth of an inch long this inter- 
nal parasite has become large 
enough to destroy it. The Apan- 
teles larva then makes its way 
from the body of the caterpillar, 
forms a cocoon (PL III, fig. 1), 
and early in June the adult para- 
site emerges. This is the time of 
year when small caterpillars of the gipsy moth are feeding, and the 
parasites attack these caterpillars and pass through one generation 
with the gipsy moth as a host. 
Another species which attacks both the gipsy and brown-tail 
moth caterpillars is a parasitic fly known as Compsilura concinnata 
Meig. (PL III, fig. 2). This insect is about the size of the house 
fly, although its habits are strictly those of a caterpillar parasite. 
Early in the spring the female fly deposits a small maggot in the 
body of the larva of the brown-tail moth which feeds inside the 
body of the caterpillar and becomes full-grown early in June. At 
this time the maggot burrows through the epidermis of the host 
and forms a puparium from which, in about a week, the adult fly 
emerges. This brood attacks the gipsy-moth caterpillars, the adult 
Fig. 3.— Apanteles lacteicolor: Adult female and co- 
coon. Much enlarged. (Original.) 
