Raphidiomorpha†Priscaenigmatomorpha Snakeflies are a group of predatory insects comprising the order Raphidioptera with two extant families: Raphidiidae and Inocelliidae, consisting of roughly 260 species.

In the past, the group had a much wider distribution than it does now; snakeflies are found in temperate regions worldwide but are absent from the tropics and the Southern Hemisphere.

An adult snakefly resembles a lacewing in appearance but has a notably elongated thorax which, together with the mobile head, gives the group their common name.

Adult snakeflies are easily distinguished from similar insects by having an elongated prothorax but not the modified forelegs of the mantis-flies.

The two pair of dragonfly-like wings are similar in size, with a primitive venation pattern, a thickened leading edge, and a coloured wingspot, the pterostigma.

Before mating, the adults engage in an elaborate courtship ritual, including a grooming behaviour involving legs and antennae.

The pupa is able to bite when disturbed, and shortly before the adult emerges, it gains the ability to walk and often leaves its cell for another location.

If the larvae begin pupation in the late summer or early fall, they can take up to ten months before the adults emerge.

[5] Insects reared at constant temperatures in a laboratory may become "prothetelous", developing the compound eyes and wingpads of pupae, but living for years without completing metamorphosis.

[8] Typically 5-15% of snakefly larvae are parasitized, mainly by parasitoid wasps, but rates as high as 50% have been observed in some species.

[5] During the Mesozoic era (252 to 66 mya), there was a large and diverse fauna of Raphidioptera as exemplified by the abundant fossils that have been found in all parts of the world.

[5] Several extinct families are known only from fossils dating from the Lower Jurassic to the Miocene,[9] the great majority of them belonging to the suborder Raphidiomorpha.

[10] Molecular analysis using mitochondrial RNA and the mitogenome has clarified the group's phylogeny within the Neuropterida, as shown in the cladogram.

[15] Two suborders of Raphidioptera and their families are grouped below according to Engel (2002) with updates according to Bechly and Wolf-Schwenninger (2011) and Ricardo Pérez-de la Fuente et al. (2012).

[6] An unidentified North American species was introduced into Australia and New Zealand in the early twentieth century for this purpose, but failed to become established.