running along sandy stream banks or along woodland trails on bright, sunny days 
from early spring to fall. They will often stop, turn, and assume an aggressive 
posture toward intruders. This habit and the way they pounce on their prey has led 
to their common name. In striking contrast to the active adults, the larvae wait for 
prey to fall into conical, vertical burrows in soil. 
Family Cupedidae 
Cupedids 
Beetles in this family are not of economic importance. Both adults and larvae 
occur in moist, badly decayed wood or under bark. Cupes concolor Westwood is a 
common, widely distributed species, sometimes found in structures of pine or oak. 
Adults have flattened bodies, 7 to 11 mm long. They are grayish brown and densely 
covered with scales. The larvae have a peculiar elongate, fleshy appearance and are 
25 mm long. Each fleshy five-jointed leg is armed with a movable claw, a 
characteristic common to predacious forms. These are considered to be the most 
primitive of all beetles. 
Family Silphidae 
Carrion Beetles 
Carrion beetles are often seen on animal excrement or around the bodies of dead 
animals in the forest. Many of the more commonly observed species are in the 
largest genera, Si/pha and Nicrophorus. Adults of various species range from 10 to 
35mm in length. Their black bodies are often ornamented with yellow or red on the 
prothorax or elytra. Their bodies are soft and robust, usually elongated but some- 
times circular. Several of the species of small size, like Agathidium oniscoides 
Palisot de Beauvois, apparently act as scavengers under the bark of logs and dead 
trees in galleries of bark beetle-infested hardwoods. 
Family Histeridae 
Hister Beetles 
Hister beetles have widely varied habits and habitats. Adults as well as larvae are 
mostly carnivorous. Many are predacious on other adult insects and their larvae. 
Habitats include excrement, carrion, decaying fungi, fermenting sap, beneath bark, 
in ant and termite colonies, or in nests of small mammals and birds. Adults are 
generally small (2 to i0 mm), sluggish, hard-shelled, and often with shortened 
elytra. Most can feign death, drawing in their appendages when disturbed. The 
species with flat bodies live under bark, often of only certain tree species, appar- 
ently because they are predacious on a pest of the particular tree, e.g., Hololepta 
spp. under bark of poplar and yellow-poplar trees. The species with cylindrical 
bodies are found in galleries of bark beetles and wood borers, e.g., Plegaderus spp. 
prey on eggs and larvae. 
Family Byrrhidae 
Byrrhids 
These beetles are oval, convex, and usually black, | to 10 mm long. The head is 
deflexed, retracted, and usually concealed from above. The hard-bodied, slow- 
moving adults retract their appendages when disturbed to form a compact ball and 
thus are referred to as pill beetles. Adults and larvae are herbivorous. 
Although several species of the genus Byrrhus are abundant and cause much 
damage to tree seedlings, specimens are difficult to find because the adults are 
nocturnal. Adults are 5 to 10 mm long, black, and densely covered with grayish 
hairs. The distribution of this genus apparently 1s limited to Alaska, Canada, and 
the contiguous Northern States. 
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