602 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
Stylocryptus subclavatus (Say) commonly attacks numerous species 
of tenthredinid cocoons throughout the United States. Furniss and 
Dowden (176) reported that of the cocoons of the hemlock sawfly 
(Neodiprion tsugae), which were collected near Sweet Home, Oreg., 
in 1936 and which produced parasites, about 10 percent had been 
attacked by S. subclavatus. It has also been reared from J. sertifer 
in New Jersey. The adults vary considerably in size depending on the 
host attacked. The larger specimens are about 54, inch long. They 
have a black thorax, a shiny red abdomen, and red legs. F emale an- 
tennae are yellowish on the basal half and dark at their tips. Females 
y 
Ficure 184.—Hemiteles tenellus, female. 
oviposit through the host cocoon, first paralyzing the host prepupa 
and then laying a large external egg. The parasite larva feeds exter- 
nally, completing development and spinning a light cocoon within the 
host cocoon. The winter is spent in this stage. Pupation takes place 
in the spring, and the adult parasite emerges rafter cutting an exit hole 
in the host cocoon. Two or even more generations may “develop i ined 
year. 
Hemiteles tenellus (Say) (fig 184) is one of the most common of 
all our hyperparasites, and has been abundantly reared from the 
cocoons of many species of Ichneumonoidea throughout the whole 
country. It may occasionally act as a primary parasite of certain 
Tenthredinidae but its injury as a secondary greatly exceeds its value 
as a primary parasite. Muésebeck and Dohanian (310) gave an ex- 
cellent account of ZZ. tenel/us as a parasite of Apanteles melanoscelus. 
The adults vary considerably in size depending on the size of the host 
attacked. Those reared from A panteles cocoons are about 1% inch long. 
= - ~ =. _ So 
