These beetles have a certain resemblance to spiders, for they have very long legs and a marked constriction between the thorax and the arched abdomen.
Many of the species are practically speaking omnivorous. The newly hatched larvae are very active, but once they reach a source of food they soon become fat and almost immobile. They can spin a kind of silk and often sit sheltered in loosely spun cocoons. The fully grown larvae sometimes leave the material they have been living in, even biting through very tough packaging. They then spin a whitish cocoon and pupate.