The Encyclopedia Americana (1920)/Prionidæ

PRIONIDÆ, a family or subfamily of longicorn beetles distinguished from its allies by the margined and usually toothed thorax. They are mostly insects of large size and robust form. Their larvæ are large, soft grubs with small heads but powerful jaws, which bore in wood and are very destructive. They rest in a nearly straight position, not bent or doubled. A number of conspicuous species are found in the United States, several of the most common belonging to the genus Prionus, in which the thorax bears three marginal teeth on each side, the joints of the long antennæ fit into one another in an intricate fashion and number from 12 to 27. These insects are nocturnal, and the males are said to fight fiercely for possession of the females. One of the larest species is P. brevicornis, a common black beetle, which flies about in a heedless fashion at dusk. The huge larvæ, as large as a man's finger, live for three years; and are very injurious to the roots of poplar and other trees. A smaller and more slender beetle is Orthosoma unicolor which bores passages through the roots of grape vines. Other species are less destructive, confining their attacks chiefly to the dead wood of stumps and decaying tree trunks. Consult Fabicius, ‘System Eleutheratorum’; Olivier, ‘Entomologia ou Histoire Naturelle des Insects’; Gyllenhal, ‘Insects Suecica’; Dejean, ‘Species Général des Coléoptères.’