236 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
KEY TO THE BORERS IN OLDER WOOD IN MOIST CONDITION OR IN CONTACT WITH 
THE GROUND—Continued 
5. Three eye spots or ocelli on each side of head; body cylindrical 
Stenodontes and Archodontes (Mallodon), p. 252 
One ocellus on each side of head; body wedge shaped, tapering pos- 
CeriorlysAn pine sss ee ee ee Prionus pocularis, p. 262 
KEY TO THE BORERS IN DRY, SEASONED WOOD 
These borers, termed ‘*powder-post borers,’ continue to work year 
after a year in the same wood until nothing is left but a thin outer shell 
filled with a mass of powder. Indication of their activity is the 
presence of small piles of powdery dust falling and collecting beneath 
the infested timbers. Certain of these borers attack only recently 
cut wood, but if the wood, after being attacked, is placed in buildings 
or stored in drier situations, the larval period is prolonged for several 
years. Under normal conditions these larvae would have transformed 
into adults and emerged in a year or two. Cases are on record where 
normally a l-or 2-year larval period has been thus extended to 8 or 
12 years. 
The classes of wood most frequently damaged are stored lumber 
exposed to attack before storing, structural timbers in houses, espe- 
cially rafters and beams, and often bridge trestling. 
Three ocelli on each side of head; boring in coniferous woods 
Hylotrupes bajulus, p. 248 
One ocellus on each side of head: 
Under side of mouth frame bearing four small projecting tubercles; boring 
in coniferous woods_____-__- Callidium antennatum; C. janthinum, p. 240 
Mouth frame not so toothed: 
Borinesin- bamboors. 4422 eee sen eee we Chlorophorus annularis, p. 240 
Boring in hardwoods 
Legs minute, smaller than palpi: 
Under side of prothorax bearing a triangular smooth white 
BRC: POs ON hee ae ye Smodicum cucujiforme, p. 268 
Under side of prothorax not so marked; legs very small; dorsal 
and ventral surfaces of body dull, finely granulated 
Neoclytus caprea; N. acuminatus, p. 253 
Legs: distinct;-largersthanspaloi= ese eee Eburia, p. 245 
DISCUSSION OF THE ROUNDHEADED BORERS 
The pine-bark borers, Acanthocinus spp., are elongate, rather de- 
pressed beetles, from 10 to 25 mm. in length. The body « color is usually 
black, mottled, or striped with gr ayish white or brown pubescence. 
The antennae are extremely long, the basal joints fringed with hairs 
beneath, and the females have an elongated ovipositor. The larvae 
are rather depressed, having the head longer than wide and very flat, 
the mandibles are long, slender, and obliquely poimted at the apex. 
The pronotum and ampullae are posteriorly velvety pubescent. The 
larvae are legless and have no spine on the last segment. 
Certain species occur in all parts of the United States, chiefly in 
pines, but also in spruce and fir. Acanthocinus nodosus (F.) is a 
large conspicuous form common in the Southeast; A. obsoletus (Oliv.) 
is a smaller form of the Northern States. From early to late in the 
summer the adults fly and lay their eggs in dying pines, either im a scar 
enawed by the female or in holes made by scolytid beetles. The larvae 
of some species feed entirely in the bark, whereas others go beneath 
the bark, making extensive meandering mines. AII complete develop- 
ment in one season. ‘The pupal cell is constructed in the bark. 
