6 



BULLETIN 204, U. S. DEPARTMENT OE 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 



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Fig. 3. — Apanteles lacteicolor: Adult female and co- 

 coon. Much enlarged. (Original.) 



