Embioptera 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
Bombyx mandarina true or mulberry silkmoths. The origin of the domesticated silkmoth is enigmatic. It has been suggested that it is the survivor of an extinct species which diverged from the ancestors of "Bombyx mandarina" millions of years ago. However, this is based on an untenable molecular clock hypothesis that assumes that wild and domestic silkmoths evolved equally fast after their lineages diverged. Rather, the effects of artificial selection have accelerated evolution in the domestic form to a point where it is hard to trace the origin of the numerous breeds of domestic silkworms even with the most modern molecular phylogeny methods.