(Embioptera, Webspinners)

Edward S. Ross

California Academy of Sciences

Embiidina (Embioptera, "webspinners," "foot spinners," "embiids") are warm-climate-adapted insects. Only about 300 species are named, but the order perhaps comprises about 2000 species. Embiids are perhaps most closely related to stoneflies and stick insects (Phasmida) but, probably since Carboniferous or Permian times, have followed their own specialized evolutionary line. The most peculiar feature of all embiids, regardless of developmental stage or sex, is an ability to spin hundreds of strands of silk with each stroke of the greatly enlarged, gland-packed basal segment of the foretarsi.

The silk is formed into narrow galleries serving as protective runways in or on the food supply—weathered bark, lichens, moss, or leaf litter. In arid regions the galleries extend deep into soil and there serve as refuges from heat and desiccation. The primordial habitat is tropical forest, where predation-reducing galleries of most species radiate on edible surfaces of tree trunks. When disturbed, an embiid quickly darts backward into the depths of the labyrinth or into a crevice beneath such cover.

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