56 College of Forestry. 
burrows containing many of the mites numerous shrunken 
or collapsed larvae and eggs may be observed. There can 
be little doubt that Sevus pom is responsible for this as in 
every case they were the only inhabitants of the burrows 
aside from the original builders. 
Three species of parasitic Hymenoptera were bred from 
pine limbs containing only the burrows of P. hopkinsi. The 
largest of these of which there are three specimens belong 
to the family Pteromalidae and gerus Metopon. It is prob- 
able that these are parasitic upon the larvae of P. hopkinsi 
as it is known that closely allied species are parasitic upon 
bark beetles as well as upon the larvae of other insects. ‘The 
other two Hymenoptera belong to the family Mymaridae 
and are both probably egg parasites. These are Ooctonus 
quadrisignatus Girault, a new species represented by three 
females, and Polynema sp (%) represented by one male. No 
records were found of either of these genera being parasitic 
upon the eggs of bark beetles and they have been most com- 
monly bred from the eggs of jassids and membracids. It is 
possible that the individuals appearing in the breeding jar 
may have emerged from the eggs of tree hoppers or leaf 
hoppers deposited upon the bark and infested before the 
material was placed in the breeding jars. It may have been 
merely a coincidence that the adult mymarids emerged in 
considerable numbers during the height of the breeding 
season of Pityogenes. 
Host Pranrs.— The favorite food plant of P. hopkinst 
is the white pine, Pinus strobus. According to Hopkins 
(1898, 1893a) Prtyogenes sparsus by which name he then 
called the species under discussion is also found in other 
pines in West Virginia. He does not, however, designate the 
species in which it was actually found, but in addition to 
Pinus strobus he also mentions that P. echinata, P. rigida, 
P. virginiana, P. pungens and oceasionally P. taeda and P. 
resinosa are found in that locality. It is nearly certain that 
any of these would serve as a food plant for the adults and is 
possible that they might serve as breeding places as well. 
However, a distinction should be made between hosts which 
will serve as food and those in which the beetles will breed. 
