tent caterpillar, common name for the larvae of the members of a family of moths (Lasiocampidae), easily recognized by the large silk tents, or webs, that the larvae construct during the spring in the crotches of trees, particularly apple and cherry trees. Tent caterpillars are hairy and usually brightly colored, with blue and yellow spots. Periodically they become serious orchard pests and occur in large enough numbers to defoliate whole trees and damage the fruit. Many larvae live gregariously within the tent, which they use for shelter during the night and in rainy weather. During the day, the larvae leave the tent and feed on the leaves in nearby branches.

The best-known tent maker is the Eastern tent caterpillar, Malacosoma americanum. In addition to being an orchard pest, it has been linked to mare reproductive loss syndrome (MRLS), in which apparently healthy mares experience high rates (more than 70% in experimental studies) of aborted fetuses or stillborn foals. An outbreak of MRLS resulted in the lost of more than 5,000 foals in Kentucky in 2001. Elimination of caterpillar populations, by removing host trees or eradicating the caterpillars, or otherwise avoiding horse contact with the caterpillars and their waste appears to prevent the syndrome. Other species of Malacosoma occur both in E and W North America and have been known to defoliate large areas by attacking a variety of forest and shade trees. Not all species build tents; despite the name forest tent caterpillar, M. disstria, at times an extremely destructive pest that migrates by the millions to new food plants, never weaves a tent.

The tent caterpillar pupates within the oval white cocoon it spins, and the adult emerges during midsummer as a reddish brown or gray, medium-sized, stout-bodied, hairy moth with feathery antennae. After mating, the adult deposits several hundred eggs, covered by a thick, foamy brown crust, in bands around the twigs of the host tree. The eggs overwinter until the early spring when they hatch. Larvae from several egg masses congregate near a fork in a limb and form the tent by crawling about, leaving silk behind. Removing egg masses during the winter or removing tents in the early spring and soaking them in kerosene or burning them, are the most effective means of control.

Tent caterpillars are classified in the phylum Arthropoda, class Insecta, order Lepidoptera, superfamily Bombycoidea, family Lasiocampidae.

tent, portable shelter of canvas, skins, felt, matting, or other material usually supported by poles and used chiefly by nomads, hunters, and campers. Tents have been used by pastoral peoples since ancient times and are mentioned in the Old Testament and in Homer. Persian tents, usually circular, were early noted for rich hangings and rugs. Army tents developed by ancient peoples include the small, skin-covered tents of the Greeks and the Roman tents of canvas supported by two upright poles and a ridgepole. Medieval military tents were round or oval and were often lavishly hung with silks or furs. Army tents were widely used in Europe in the 17th and 18th cent. but are now employed chiefly for training purposes. Modern types include bell tents with a central pole; the A tents with sides sloping from a ridgepole; and the marquee, a large field tent, used for mess or hospital shelters. Smaller tents for recreational camping and backpacking include dome, "flashlight," and other designs that typically use shock-corded aluminum or fiberglass poles and lightweight fabrics. The yurt, a circular, felt-covered structure of latticework surmounted by curved poles fitted at the top into a ring forming a smoke hole, has long been used by nomads of the Asian steppes. Desert tribespeople of W Asia and North Africa generally use a ridgepole tent. One of the simplest tent forms is the windbreak, which was mainly used in Patagonia. See also tepee.

oxygen tent, device used to maintain a patient in an oxygen-rich environment. The oxygen tent is composed of a clear plastic sheet suspended over the bed and tucked beneath the mattress to provide an almost airtight compartment. The oxygen supply and temperature are controlled by means of gauges. Zippers on the sides of the tent provide access to the patient. The device is particularly useful in the treatment of heart and lung disorders that limit the body's supply of oxygen and thus necessitate a higher concentration of the gas than is normally present in the air.

Kasha-Katuwe Tent Rocks National Monument: see National Parks and Monuments (table).

Building that uses masts or poles and tensile membrane (e.g., fabric or animal skin) enclosures. Tent structures are prestressed by externally applied forces so that they are held taut under anticipated load conditions. Tents have been the dwelling places of most of the world's nomadic peoples, from ancient times until the present. The traditional Bedouin tent consists of a rectangular membrane of strips of woven camel hair that is strained on webbing straps and secured with guys over a rectangle of poles. The American Plains Indians developed the conical tepee. The Central Asian nomadic pole dwelling, or yurt, uses skins and textiles as its covering. Seealso membrane structure, pole construction.

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Any moth larva of the genus Malacosoma (family Lasiocampidae). Tent caterpillars are often brightly coloured. Congregations of the eastern tent caterpillar (M. americanum) of eastern North America spin huge, tent-shaped communal nests in forked tree branches. Eggs the moth deposits on a tree in midsummer hatch in spring. The hatched caterpillars migrate to a tree crotch and construct a silken tent, which they leave each day throughout the summer to feed on the surrounding leaves. The forest tent caterpillar (M. disstria) is common in the southern U.S.

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