History and Habits of Pityogenes. Bb 
as Sews pom Parrott. Prof. H. EK. Ewing writes as fol- 
lows concerning this species. ** This species —- —- — — is 
found generally throughout most of the U.S. on and under 
bark. It is predaceous and is one of the most important 
enemies we have of the pear-leaf blister-mite and the various 
species of spider mites.” Parrott, Hodgkiss and Schene 
(06) report it as “‘ Very abundant — upon infested trees 
and undoubtedly materially assisted in reducing the number 
of blister mites.” The other mite is larger and belongs to 
the genus Gamesus, but as it was immature the species was 
not determined. 
Both of these species were often found in considerable 
numbers both in the brood burrows and upon the bodies of 
the adult beetles, not only in the breeding jars, but also 
under natural conditions out of doors. In connection with 
his account of parasites of Phloetribus liminaris Harris, Gos- 
sard (713) says: “ Mites, found in considerable numbers in 
the burrows and clinging to the hairs of the beetle are 
apparently not parasites but feeders on the excrement and 
other decaying matter within the burrows. They attach 
themselves to the beetles in order to procure easy trans- 
portation from one place to another.” In the case of 
Seius pomi, at least, this interpretation would hardly seem 
to agree with my observations. This mite seems to be an 
external parasite on both the adult and immature stages 
of P. hopkinst. Adults harboring a dozen or more of these 
quite active little animals have been observed carefully 
under the microscope and there can be no doubt that the 
latter are injurious to their hosts. The mites appear to be 
successful in their attack upon the adults only when they 
obtain a firm hold upon the membrane at the juncture of 
the legs and body. When this vulnerable point is attacked 
the beetle makes frantic and often successful efforts to ward 
off the danger by threshing about violently with his legs. 
Without doubt, however, the eggs and young larvae of P. 
hopkinsi are the stages which suffer most frequently from 
the carnivorous habits of P. pomi. An actual attack upon 
either of these stages has never been observed, but in brood 
