30 College of Forestry 
with Polygraphus rufipennis and Dendroctonus simplex 
especially. The clerid Cymatodera bicolor and the lamperid 
Podabrus diadema were also bred from bark infested with 
P. rufipennis. Both of these are perhaps predaceous, 
although no reference to the food habits of the latter species 
was found in the literature. 
A number of hymenopterous parasites were also bred from 
material containing the brood of these various species of 
scolytids. Of these the most common is Spathius tomict, 
which was constantly associated with P. rufipennis, H. piceae 
and D. simplex. It was especially numerous in Trees I, 1X 
and X. Of these Tree 1X was from near Wanakena and of 
scolytids contained only the brood of P. rufipennis. Tree X 
contained numerous brood not only of this bark beetle but 
also of H. piceae. Tree I contained all three scolytids and 
all regions of the tree gave rise to specimens of this small 
parasite. There can be no doubt that S. tomici is parasitic 
on both P. rufipennis and EH. piceae, as different lots of 
material which were practically pure cultures of either one 
or the other of these species yielded the parasite when placed 
in a breeding jar or cage. We cannot state so definitely that 
D. simplex serves as its host, for the reason that the Dendroc- 
tonus infested material from which the parasite was bred 
contained also the brood galleries of P. rufipennis. How- 
ever, it seems very likely that a considerable number of small 
bark beetles may act as host for Spathius tomici. 
Heterospilus sp., Spathius sp., Spintherus pulchripennis, 
and Cheiropachus sp. were obtained from material contain- 
ing both P. rufipennis and FH. piceae, and each may be para- 
sitic upon either one or both of these bark beetles. Hury- 
toma sp. was bred from material containing the brood of 
P. rufipennis and is probably parasitic upon it. Several 
specimens of a small undetermined chalcid were obtained 
from material containing P. rufipennis and D. simplex and 
may be parasitic on either one or both of these or may be a 
hyperparasite upon their parasitic forms. A number of 
specimens of Medeterus sp. were bred from material con- 
taining large numbers of P. rufipennis and some EL. piceae. 
