216 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
and maple, occur occasionally in buzzards’ nests, as do those of 
Pseudocistela brevis (Say). The latter species has also been found in 
the debris present in the nest of a ruffed grouse. Larvae of Lobopoda 
punctulata (Melsh.) occur in dead knots of hardwood trees, such as 
ash, and also in the soil of peach orchards. Larvae of /somera sericea 
(Say) have been found in the soil beneath decaying wood. 
Famity TENEBRIONIDAE 
The Darkling Beetles 
The darkling beetles are small to very large beetles of exceedingly 
variable form and sculpture, often clumsy and slow- -moving and usually 
sombre dark-brown or black. They have antennae of beadlike joints, 
and the hind tarsi have four segments instead of five, as have the other 
two pairs. 
The larvae are elongate, slender, and usually more or less cylindrical, 
and the body covering is often horny and tough, resembling that of 
the wireworms. The head is more or less elobular and protruding, 
with clypeus and labrum distinct and with. deeply retracted mouth 
parts. The maxillary stipes is free, the mala simple and undivided, 
the cardo of one piece, and the hypophary ngeal sclerome is biscuspidate 
or tricuspidate, and usually heavily scler otized and attached to a well- 
developed bracon and grinds against a large molar structure on the 
mandibles. The legs are well developed, with five segments, the first 
pair often the largest. ‘The spiracles are annular, the ninth abdominal 
segment is terminal, and often ends in peculiar horny armature. 
Although the Tenebrionidae is one of the largest families in the 
order, it is of little economic importance in the forests. Several 
species, however, are economically important to germinating seed, as 
well as to stored grain and cereals, and others, like the mealworms, are 
sold extensively as food for birds. A few species of Strongylium at- 
tack living trees at stubs or wounds and bore into the sohd wood. They 
are probably associated with fungi. By far the greater number of 
forest forms are scavengers found under the bark of dead and dying 
or rotten trees and logs where they feed on decaying vegetable matter. 
Many species are definitely associated with decay or even live in the 
fruiting bodies of fungi. With the exception of the genus Corticeus, 
the larvae are more fr equently seen than the adults. These beetles are 
frequently observed making their way in and out of ventilation holes 
and in the runways of bark- beetles in infested trees. The larvae are not 
gregarious in the wood, as are those of the comb-clawed beetles. 
KEY TO LARVAE OF THE MORE COMMON WOOD- AND FUNGUS-INFESTING 
TENEBRIONIDAE 
1 Terminal’segment. unarmed = 3s Se ee ee a ee 2 
Terminal segment armed with two spines____-______------------ 6 
2. Terminal segment dorsally excavate and with sharp margin; body 
cylindrical and well sclerotized, length to 34 mm.; in decaying 
logs-and: stumps! 32 a ee ee eee ee ee Meracantha 
Terminal segmentxotherwiSe esa ee ee ee 3 
3. Terminal segment broadly rounded; hypopharynx not projecting, 
transverse, rectangular and weakly sclerotized; body subeylin- 
drical, soft; length to 8 mm.; under bark of beetle-attacked trees 
and logs Ae? Mer SOLE Ayo CU, oo fi ul Why Corticeus (Hypophloeus) 
Terminal segment pointed; hypophary nx projecting, strong, vari- 
able‘in: shape... oye See ee oe ee eee eee ae 1 
