Webspinners
Embiidina
Summary 4
The order Embioptera, commonly known as webspinners, are a small group of mostly tropical and subtropical insects, classified under the subclass Pterygota. The order has also been referred to as Embiodea or Embiidina. The name Embioptera ("lively wings") comes from Greek, εμβιος, embios meaning "lively" and πτερον, pteron meaning "wing", a name that has not been considered to be particularly descriptive for this group of fliers, perhaps instead referring
Behaviour and ecology 5
The embiopteran diet varies between species, with available food sources changing with varying habitat. The nymphs and adult females are herbivorous, feeding on leaf litter, moss, bark and lichen. As stated above, adult males do not eat at all, meaning the majority die rapidly due to depleted energy resources (starvation).
Most, if not all embiopteran species, like many other species of insect, are gregarious, specifically displaying subsociality. This particular kind of social behaviour involves the female guarding her eggs and then caring for her young (right) for several days after hatching. In some species this parental care even involves the female feeding the nymphs with portions of chewed-up leaf litter and other food sources.
Subsociality is a trade-off for the female, as the energy and time that is exerted into caring for her young is rewarded by giving them a much greater chance of surviving and carrying on her genetic lineage. Some species do share galleries with more than one adult, however most groups consist of one adult female and her offspring.
Embiopterans produce a silk thread highly similar to that produced by the much better known silkworm Bombyx mori. The silk is produced in spherical secretory glands in the tarsi of the embiids enlarged forelimbs, and can be produced by both adults and larvae. Unlike Bombyx mori and other silk-producing (and spinning) members of both Lepidoptera and Hymenoptera, which only have one pair of silk glands per individual, some species of embiid are estimated to have up to 300 silk glands: 150 in each forelimb. These glands are linked to 'setae-like cuticular process called a silk ejector', and their exceedingly high numbers allow individuals to spin large amounts of silk very quickly, creating extensive galleries (see image below). The silk web is produced throughout all stages of the embiopteran lifespan, and requires very little energy output.
The ‘galleries' produced by embiopterans are tunnels and chambers woven from the silk they produce. These woven constructions can be found on substrates such as rocks and the bark of trees, or in leaf litter. Some species camouflage their galleries by decorating the outer layers with bits of leaf litter or other materials to match their surroundings (see image). The galleries are essential to their life cycle, maintaining moisture in their environment, plus offering protection from predators and the elements while foraging, breeding and simply existing. The only occasion when an embiopteran will leave the gallery complex is when winged males fly out or wingless males walk out in search of a mate, or when females explore the area immediately surrounding them in search of a new food source. On detection of a potential predator or threat, the embiids retreat into their galleries, and some species have even been observed to 'play dead' until the threat is no longer present.
Webspinners continually extend their galleries into new food sources, and expand their existing galleries as they grow in size. The insects spin silk by moving their forelegs back and forth over the substrate, and rotating their bodies to create a cylindrical, silk-lined tunnel. Older galleries have multiple laminate layers of silk. Each gallery complex contains a number of individuals, often descended from a single female, and forms a complex maze-like structure, extending from a secure retreat into whatever vegetable food matter is available nearby. The size and complexity of the colony varies between species, and they can be very extensive in those species that live in hot and humid climates.
Sources and Credits
- (c) Jon Mortin, some rights reserved (CC BY), uploaded by Jon Mortin
- (c) Benjamin K Maples, some rights reserved (CC BY-NC), uploaded by Benjamin K Maples
- no rights reserved, uploaded by Jesse Rorabaugh
- Adapted by Will Kuhn from a work by (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Embiidina
- (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Embioptera
