212 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
Famities BORIDAE, PYTHIDAE, and PYROCHROIDAE 
The Flat Bark Borers 
Several forms of flat bark borers are mentioned together because 
of their similarity in appearance. Both adults and larvae are greatly 
depressed, an adaptation to the habits of feeding between the fairly 
tight bark and wood of dead trees and logs. 
‘Pytho americanus Kby. is a brown, soft-bodied beetle about 15 mm. 
long with the thorax rounded and narrowed behind, not margined, 
and the elytra entire and deeply striate. Boros unicolor Say is black, 
slightly smaller, more elongate, slender, and the elytra are smooth. 
Neopyr ochroa femoralis Lec., about 15 mm., and Dendroides cana- 
densis Lec., about 12 mm. long, are depressed, contrastingly colored 
beetles with black elytra and yellowish thorax. The elytra are soft- 
textured, widening behind and covering the abdomen. The head and 
prothorax are very small and narrow, the former restricted into a 
neck, and the antennae serrate or flabellate. 
The larvae of all four forms are elongate and extremely depressed, 
and the ninth abdominal segment is fitted with pronged armature 
(fig. 45, 4). The forms can be separated by characters mentioned 
in the key to families. 
Famity OTHNIIDAE 
Othnius fasciatus Bland is only occasionally found in the Appala- 
chian region in dead pines infested by the southern pine beetle, but 
the western species are extremely abundant in trees killed by bark 
beetles. The gray, hairy, active adults are predaceous and resemble 
clerids, but the larvae are probably scavengers. The larvae resemble 
the Colydiidae, from which they can be distinguished by the fact that 
the Othnidae have an armature on the ninth abdominal tergum. 
Famiry MELANDRYIDAE 
The Melandryid Bark Borers 
The melandryids are small to large beetles of various forms, usually 
elongate to oval, loosely jointed, having the thorax margined at the 
sides, filiform antennae, front coxal cavities open behind, and four- 
jointed hind tarsi. The larvae are elongate, fleshy, cylindrical or sub- 
depressed forms, superficially resembling cerambycid larvae, from 
which they are readily distinguished by the following characters: 
Deeply retracted mouth parts; free maxillary stipes; simple mala ; 
mentum and submentum often heavily chitinized; cardo two-jointed; 
maxillary sclerite not chitinized; and the mandible with a poorly 
developed, smooth molar structure. The legs are well developed and 
have five joints. The ninth abdominal segment is terminal and often 
bears a pair of spines, and usually several abdominal segments have 
the pleural regions swollen and protuberant. 
Although the adults of these forms are seldom seen, the larvae are 
very commonly encountered under the bark or in the wood of dead logs. 
They are usually associated with wood-decaying fungi—some appar- 
ently specific with certain fungi. Some of the more commonly met 
forms are: Melandrya striata Say, found in a wide variety of hard- 
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