#raphidioptera

Snakeflies are considered a “relict” taxon, having a much wider distribution in the past, and having reached their apex of diversity during the Cretaceous, before undergoing substantial decline when the K–Pg Extinction Event wiped out all but the most cold-tolerant species of snakefly. Today, only 260 species remain, and they are relegated only to temperate, more northern regions.

Like most holometabolous insects, snakeflies go through a four-stage life cycle consisting of egg, larva, pupa and adult. In most species, the larvae develop under the bark of trees. They may take several years before they undergo metamorphosis, requiring a period of chilling (around 0 °C [32 °F]) before pupation can take place. If the larvae begin pupation in the late summer or early fall, they can take up to ten months before the adults emerge. Interestingly though, the pupa is able to bite when disturbed, and shortly before the adult emerges, it even gains the ability to walk and can even leave its cell for another location if necessary. Eat your heart out, butterflies.

Snakeflies reared at constant temperatures (ie without a chilling period) in a laboratory may become "prothetelous", developing the compound eyes and wingpads of pupae, but living for years without completing metamorphosis.

Adult snakeflies engage in elaborate courtship rituals before mating, which involve mutual grooming behaviour involving both antennae and legs. In Raphidiids, mating takes place in a "dragging position", while in Inocelliids, the male adopts a tandem position under the female. Snakefly copulation may last for up to three hours in some Inoceliid species. Follow bestanimal for more Bug Sex Facts.