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Embiids

galleries insects silk spin

Embiids are small, cylindrical, soft-bodied insects in the order Embioptera that spin tubular galleries of silk, an ability that gives them the common name web-spinners. They have chewing mouthparts, and undergo paurometabolism, or gradual metamorphosis, exhibiting a definite egg, nymph, and adult stage. In the phylogeny, or evolutionary history of the class Insecta, embiids are thought to be most closely related to the orders Dermaptera (the earwigs) and Plecoptera (the stoneflies).

A distinguishing morphological feature of the webspinners is that the silk glands are in the tarsal segments of the front legs. Another unique characteristic of these insects is that the wings of the males are flexible when the insect is not in flight. Their wing veins are hollow, and fill with blood in order to stiffen the wing for flight.

Embiids are gregarious, or group-living, insects in which the wingless females live in silken galleries where they care for their young. The males of this order are often, but not always winged, and do not feed as adults. Rather they die soon after finding and mating with a female. Individuals in all developmental stages have the ability to spin silk. They spin galleries in the soil, under bark, in dead plant matter, in rock crevices, and other such inconspicuous substrates. The females and nymphs living in the galleries are flightless but they are adapted to run backwards through the tunnel to flee potential predators that may discover the opening of the chamber.

These secretive insects are rare, with only 200 species known to exist, most of which are tropical. In the United States, there are ten species, all of which have a southern distribution. The main food source of Embioptera is dead plant matter, and this fact, as well as their relative rarity, make embiids of little known economic significance to humans.

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