Embioptera: The Silk Spinning World Of The Webspinners

The Embioptera (Webspinners) are a small group of soft bodied, relatively small, gregarious insects. They can be found in most tropical and warm temperate climates. There are about 300 species world wide.

They are hemimetabolous (having a simple or very little metamorphosis i.e. no pupa) and the males usually have two pairs of nearly equal wings (though in the Australembiide the males are ‘apterous’ – wingless) while the females are apterous in all species.

Their antennae are filiform (thin and linear) with 15 to 32 segments, their mouthparts designed for biting and their compound eyes are either oval or reniform (kidney shaped) and smaller in the females than the males. They have no ocelli, their cerci are 2 segmented and the males have asymmetrical external genitalia.

The Embioptera are called Web Spinners because they are very good at spinning webs from the silk secreted by glands in the tarsi of their forelegs.

They spin themselves tunnels of silk to live in; a tunnel is normally occupied by a single female and her young. Many tunnels may be congregated together and inter-linked to form a sort of colony, though the Embioptera are not social or even subsocial. Both adults and nymphs can spin the silk to make the tunnels.

They are nocturnal, living in their tunnels by day and coming out at night to feed on plant material of various sorts – dead, living, soft and woody. The males, who probably don’t eat, enter the tunnel of the female only to mate.

Females and juveniles feed on a variety of vegetable materials, bark, dead leaves, moss and also on lichens. Males do not usually live for very long once they reach maturity.

Reproduction is normally bisexual but parthenogenesis does occur (when unfertilised ova (eggs) develop and hatch, this always results in the production of more females only). The female lays the urn-shaped or ovoidal eggs in small clusters along the sides of her tunnel. Females generally exhibit simple parental care, licking the eggs and occasionally moving them. In some species the female supplies the young with chewed plant material. The nymphs go through 4 instars before becoming adult.

Embioptera Taxonomy

The Embioptera can be divided up into three suborders and 13 families. See Tree Of Life.

Bibliography

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• Ultrastructural investigation of the ommatidia in the dark-adaptive eye of the Turkestan Embiid Embia tartara (Embioptera); Burakova O. V. and Mazokhinporshnyakov G. A.; Zoologichesky Zhurnal, 1986, Vol.65, No.11, pp.1743-1746
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