BARK, or BARQUE, a three-masted ves sel whose foremast and mainmast are square ngged, but whose mizzenmast has fore-and-aft sails only. The distinction between a barlc and a barkentine is that the latter has but one mast square-rigged, the main and mizzen being both rigged fore-and-af t.
members of the fam ily Scolytidce, and allied to the weevils. They are of an elongate cylindrical form, truncated before and behind. They mine under the bark of trees, running their winding galleries in every direction, but rarely attack living healthy trees. They are usually brown or black in color. The rounded head does not end in a snout and is deeply sunken in the thorax; the clavate antenna are somewhat elbowed, while the palpi are very short; the elytra are often hollowed at the end, and the short stout legs are toothed on the under side of the femora, and the tarsi are slender and narrow. The eggs are laid in the bark, whence the larva on being hatched bore straight into the sap wood, or mine between the bark and the sap wood, They are fleshy, cylindrical, footless larva, wrinkled on the back. When fully grown in the autumn they gnaw an exit for the beetle, talcing care to leave a little space closed in front of their burrow to conceal the pupa. The various species of Scolytus, Tomicus and Xyloterus give rise to a disease similar to fireblight, by their ravages beneath the twigs of fruit trees, causing the bark to shrivel and peel off as if a fire had run through the orchard.
Xyloterus fuscatus has been found to bore into empty wine casks and spoil them for use. The spruce forests of Maine and other parts of northern New Eng land have, since 1818, been devastated by Dendrocotonus piceaperda of Hopkins. It at tacks and kills vigorous trees in perfect health, the largest and best stands of timber suffering most from its ravages. The estimated number of adults which under favorable conditions may emerge from an average-sized tree is from 5,000 to 7,000. Hopkins estimated that an average of three pairs of beetles to the square foot of bark on 10 to 15 feet of the trunk of an average-sized tree are sufficient to kill it, and that 6,000 beetles breeding in one tree may be sufficient to kill from 20 to 25 more trees. Two other beetles (Polygraphus sufipennis and Tetropium cinnamopterum) also aid the Deu drocotonus in killing the spruce. Consult Pack ard, 'Report on the Insects Injurious to Forest and Shade Trees' (1890); Hopkins, (Insect Enemies of the Spruce in the Northeast' (Bul letin No. 28, Division of Entomology, United States Department of Agriculture, 1891).