ANT

(Top to bottom) The carpenter ant (Camponotus) may be a household pest; when some of the any member of the approximately 8,000 species of the insect family Formicidae (order Hymenoptera). Ants occur worldwide but are especially common in hot climates. All ants are social in habit; i.e., they live together in organized colonies, and they range in size from 2 to about 25 millimetres (about 0.08 to 1 inch). Their colour is usually yellow, brown, red, or black. A few genera (e.g., Pheidole of North America) have a metallic lustre. Typically, an ant has a large head and a slender, oval abdomen joined to the thorax, or midsection, by a small waist. The antennae are elbowed. The mouth has two sets of jaws: the outer pair is used for carrying objects such as food and for digging, and the inner pair is used for chewing. Some species have a powerful sting at the tip of the abdomen. There are generally three castes, or classes: queens, males, and workers. Some species live in the nests of other species as parasites; i.e., the larvae are given food and nourishment by the host workers. Wheeleriella santschii is a parasite in the nests of Monomorium salomonis, the most common ant of northern Africa. Most ants live in nests, which may be located in the ground or under a rock or built aboveground and made of twigs, sand, or gravel. Carpenter ants (Camponotus)large, black ants common in North Americalive in old logs and timbers. Some species live in trees or in the hollow stems of weeds. Tailor, or weaver, ants, found in the tropics of Africa (e.g., Tetramorium), make nests of leaves and similar materials held together with silk secreted by the larvae. Dolichoderus, a South American genus, glues together bits of animal feces for its nest. The widely distributed pharaoh ant (Monomarium pharaonis), a small yellowish insect living in houses, builds its nest outdoors only in warm climates. Army ants, of the subfamily Dorylinae, are nomadic and notorious for the destruction of plant and animal life in their path. The army ants of tropical America (Eciton), for example, travel in columns, eating insects and other invertebrates along the way. Periodically the colony rests for several days while the queen lays her eggs. As the colony travels, the growing larvae are carried along. Habits of the African driver ant (Dorylus) are similar. The fire ant (Solenopsis saevissima), introduced into Alabama from South America, had spread throughout the southern United States by the mid-1970s. It inflicts a painful sting and is considered a pest because it builds large mounds as nests. Effective, ecologically acceptable methods to control it are being sought. The life cycle of the ant has four stagesegg, larva, pupa, and adultand spans a period of 8 to 10 weeks. The queen spends her life laying eggs. The workers are females and do the work of the nest; the larger ones, the soldiers, defend the colony. At certain times of the year, many species produce winged males and queens. They fly into the air, where they mate. The male dies soon afterward, and the fertilized queen establishes a new nest. The food of ants consists of both plant and animal substances. Certain species, including those of the genus Formica, often eat the eggs and larvae of other ants or those of their own species; other species eat the liquid secretions of plants. The honey ants (Camponotinae, Dolichoderinae) eat the so-called honeydew, a by-product of digestion secreted by certain aphids. The ant usually obtains the liquid by gently stroking the aphid's abdomen with its antennae. Some genera (Leptothorax) eat the honeydew that has fallen onto the surface of a leaf. The so-called Argentine ant (Iridomyrmex humilis) and the fire ant also eat honeydew. Harvester ants (Messor, Pogonomyrmex) store grass, seeds, or berries in the nest; whereas ants of the genus Trachymyrmex of South America eat only fungi, which they cultivate in their nests. The Tes leaf-cutting ant (Atta texana) is a pest that often strips the leaves from plants to provide nourishment for its fungus beds. The social behaviour of the ants, along with that of the honeybees, is the most complex in the insect world. Slave-making ants, which include many species, have a variety of methods for enslaving the ants of other species. The queen Bothriomyrmex decapitans of Africa, for example, allows herself to be dragged by Tapinoma ants into their nest. She then bites off the head of the Tapinoma queen and begins laying her own eggs, which are cared for by the enslaved Tapinoma workers.