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Moth


Moth any of the large and varied group of insects which, along with the butterflies make up the order Lepidoptera. They are generally distinguished from the butterflies by having antennae of various types, usually not clubbed and by having nocturnal or crepuscular habits. Most moths usually have a frenulum, a hook-like device connecting the hindwing with the forewing. In contrast to slender-bodied, brightly coloured butterflies which fly at daytime, moths have stout bodies, dull colour, and fly at dusk or night time. There are however, some brightly coloured, slender-bodied moths.

Moths vary greatly in size. For example, the luna moth (Attacus atlas), one of the largest, may have a wing spread of about 30 cm. The smallest moths, belonging to a group called leaf miners have wing spread of about 3 mm. Moths live throughout the world, except in the ocean.

A moth's body, like that of any insect, is divided into head, thorax and abdomen. The head bears the antennae, eyes and siphoning type of mouthparts. A pair of antennae arises from between the eyes, often feather like. The antennae are extremely sensitive to chemicals in the air. A male moth can 'smell' the pheromone released by the female of the species from considerable distance.

Moths are important in the pollination of certain flowers. Some flowers that bloom only at night depend on night flying moths for pollination. The best known benefit to human being is probably the production of silk by the silk moth. Moth caterpillars cause extensive damage to crops and forest each year. Some species feed on woolen fabrics and other animal products.

There are more than 1,00,000 species of moths. They are grouped into various families. Some most common species of Bangladesh are mentioned below: Pyralidae (snout moths) have the labial palpi prolonged in the form of a snout. Yellow stem borer (Scirpophaga incertulas), dark headed stem borer (Chilo polychrysa), leaf folder (Cnaphalocrosis medinalis), case worm (Nymphula depunctalis) are some of the rice pests. sugarcane top shoot borer (Scirpophaga nievella), and brinjal shoot and fruit borer (Leucinodes orbonalis) are also included in this family. Rice meal moth (Corcyra cephalonica) and Indian meal moth (Plodia interpunctella) are pests of stored rice.

Noctuidae is the largest family of moths, usually dull-coloured but may have bright colours on the hindwing. A caterpillar, called cutworm (Agrotis ipsilon) causes damage to seedlings. Helicoverpa armigera is another important pest. Pink stem borer (Sesamia inferens) is a pest of rice, wheat and maize. Arctiidae or Tiger moths are small to medium in size. Many have brightly coloured patterns on their wing. Caterpillars may have a dense cover of long hairs. Jute Hairy Caterpillar (Spilosoma obliqua), sunnhemp moth (Utethesia pulchella), castor caterpillar (Pericallia ricini) are important pests.

Geometridae (Measuring worm moth) crawl by alternately looping their bodies into the air and then extending their front legs to straighten themselves. Several species are pests of forest trees in this country. Sphingidae (Hawk moths), also called sphinx moths are mostly large, robust, crepuscular or nocturnal moths. They are very swift fliers. tobacco hornworm, tomato hornworm, til hawk moth (Acherontia styx), and Herse convolvuli are some important examples of the hawk moth fauna of Bangladesh. Bombycidae includes the silk moth (Bombyx mori), that produces the silk of commerce. The larvae (silkworms) feed only on mulberry leaves and spin silken cocoons.

Saturniidae includes large to very large moths. Wings often have transparent eye-like spots. Larvae are also large and provided with spined tubercles; pupate in silken cocoons. Samia cynthia ricini feeds on castor leaves and spins silken cocoons. Cricula trifenestrata is the mango hairy caterpillar, also called the mango defoliator, a pest of mango. [Monawar Ahmad]