160 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
Faminry SILPHIDAE 
The Carrion Beetles 
The carrion beetles, as their name implies, are most commonly met 
with around the bodies of dead animals or on animal excrement in 
the forests. The larger more conspicuous forms in these associations, 
such as Si/pha or Necrodes, are frequently observed, yet are probably 
of less direct interest to the forest entomologist than a group of very 
small forms acting as scavengers, or possibly predators, under the 
bark of dead logs and trees. 
The larvae of these latter forms resemble small staphylinids in 
having jointed cerci, but the mandibles have a well-developed grind- 
ing structure or mola. One of the most common forms is Agathidium 
oniscoides Beauv., found associated with the galleries of bark beetles 
in hardwoods. 
Famitry PSELAPHIDAE 
The Ant-Loving Beetles 
The ant-loving beetles are very small brownish or black compact 
beetles, not over a few millimeters in length, closely related to the 
rove beetles, and like them, having short wing covers. They are 
mentioned only because they are frequently met with in ant and 
termite nests in logs or damp woodwork. They are supposed to be 
cared for by the ants because they furnish certain secretions on which 
the ants feed. 
One of the most common eastern forms is Batrisodes virginiae 
Casey, found in decaying logs and frequently associated with termite 
colonies. 
Famity HISTERIDAE 
The Hister Beetles 
The hister beetles, met with under bark or associated with wood- 
boring insects, are often very flat, roundly rectangular, black, shining 
forms with shortened wing covers, usually marked with deeply im- 
pressed striae. They are sluggish and slow moving, often drawing 
their legs under them and feigning death when disturbed. The larvae 
are likewise sluggish with few exceptions, and are soft-bodied, and 
like the rove beetle larvae have grasping mandibles and jointed cerci, 
but they are readily distinguished by their biforous spiracles. 
Some of the more common forms are Hololepta fossularis Say, one 
of the largest species, nearly 10 mm. in length, found under the bark 
of poplar ‘and tulip trees, where the larvae are predaceous, and numer- 
ous species of Paromalus, Plegaderus, and Hister, found in the gal- 
leries of bark beetles. They are probably all predaceous on small 
forms in these situations. 
Famiry BYRRHIDAE 
The Pill Beetles 
Several species of the genus Byrrhus are occasionally found injuring 
young trees in forest nurseries or plantations. These are small, oval, 
and strongly convex beetles about 5 to 10 mm. long, black and grayish 
colored with the body densely covered with hairs. The larvae super- 
