INSECT ENEMIES OF EASTERN FORESTS 607 
importance as a control factor. Thorpe (408) noted it as a common 
parasite of the casebearer in southern France, and gave brief biological 
notes regarding the species. The adults are small black insects, less 
than 14 inch long, with inconspicuous lighter markings on the legs. 
The wings are fuscous. Probably only one generation develops each 
year. <A very tiny egg is laid internally in a small casebearer larva. 
The host larva overwinters and the parasite hibernates in the first 
instar. Development is completed in the spring and Bassus adults 
emerge from host larval cases from about the middle of June until 
the middle of July. Casebearer larvae suitable for attack are avail- 
able from about July 15 to the end of the summer. 
Apparently all species of J/acrocentrus are internal parasites of 
lepidopterous larvae, and in most cases the host larvae live partly con- 
cealed as leaf rollers or borers. Most of the species seem to be solitary 
parasites, but some are gregarious. The latter probably develop 
through polyembryonic reproduction. At least one gregarious species, 
M. gifuensis Ashm., a parasite of the European corn borer (Pyrausta 
nubilalis) was shown by Parker (327) to develop in this manner. 
Several species are parasites of forest insects, but their life histories 
are not well known. JZ. cerasivoranae Vier. is a common parasite of 
Archips fervidana and A. cerasivorana throughout the United States. 
The adults are about % inch long and uniformly dark yellow. A 
summer generation is completed on these hosts, but it is not known how 
the parasite overwinters. Probably an alternate host is attacked. 
M. peroneae Mues. is a parasite of the black-headed budworm (Pe- 
ronea variana (¥Fern.)). 
The genus J/eteorus contains a number of species that are important 
parasites of injurious insects. Most of the species that have been 
investigated are parasites of lepidopterous larvae, but certain other 
species attack Coleoptera. 
Meteorus versicolor (Wesm.) (fig. 186), a parasite of the brown- 
tail moth (Nygmia phaeorrhoea), was successfully introduced into 
New England from Europe, and definite proof of its establishment 
was obtained in 1909. As early as 1918 it had spread over 
the entire area infested by the brown-tail moth, but records do not 
indicate that it has been of any great importance as an enemy of this 
insect. In 1926, Brown (67) found a species of Meteorus, which mor- 
phologically and biologically was identical to versicolor, acting as an 
important parasite of the satin moth (S¢¢/pnotia salicis) , in the vicin- 
ity of Budapest, Hungary. This Meteorus differed from the brown- 
tail moth parasite only in host selection. From 1929 through 1934 
rather large shipments of J/eteorws cocoons reared from the satin 
moth near Vienna and Budapest were sent to the United States. Since 
M. versicolor has never been reared from the satin moth in New Eng- 
land, a number of colonies were liberated in that area, and a number 
were also sent to Washington State for liberation against the satin 
moth there. The species apparently has not become established on the 
satin moth in New England, but Jones, Webber, and Dowden (260) 
reported its establishment in Washington, where it has become an 
important satin moth parasite. 
The adults are about 34¢ inch long, nearly unicolorous yellow, with 
darker markings on abdomen and propodeum. Oviposition takes 
place in small brown-tail moth and satin moth larvae in August and 
792440°—_49——_39 
