The snakefly is a living fossil with a neck that mimics a serpent

Nature · Published 3 October 2026 Swipe more like this →

In short: Named for their elongated prothorax, snakeflies are ancient predators that have survived since the Jurassic period. While they resemble delicate lacewings, these insects are distinct, possessing a unique, mobile head and a specialized life cycle that requires a chilling period to trigger their final transformation into adulthood.

Snakeflies, belonging to the order Raphidiodea, are easily identified by their slender, elongated necks. Unlike the related lacewings, which have downward-directed mouthparts, snakeflies possess forward-directed mouthparts and biting larval mandibles. These carnivorous insects are confined to the Northern Hemisphere, where they inhabit temperate regions. While there are more than 175 species, they are considered a relict group, having reached their peak diversity during the Cretaceous period before experiencing a significant decline.

The life cycle of a snakefly is complex and holometabolous, consisting of egg, larval, pupal, and adult stages. Females use a slender ovipositor to deposit eggs singly into the cracks of tree bark, where the immature stages develop. Unlike many other insects that complete their life cycle within a single year, snakefly larvae often require several years to reach maturity. A critical requirement for their development is a period of exposure to cool temperatures, which is necessary to induce pupation.

During the larval stage, these insects are active predators of soft-bodied arthropods. Once the larva reaches its final stage, it constructs a cell to pupate. Interestingly, the pupa is capable of movement and can even bite if disturbed. Before the adult emerges, the pupa often leaves its cell to find a more suitable location. This unique combination of a long, multi-year larval development and a specific environmental trigger for metamorphosis highlights the specialized evolutionary path of this ancient insect order.

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