Unidentified snakeflies

There are no published references that deal comprenensively with identification of British snakefly larvae. The most useful reference I'm aware of is a key to three Norwegion species: Greve, L. 2002. The order Raphidioptera in Norway. Norw. J. Entomol. 49, 81-92. But this only covers two of our species (Xanthostigma xanthostigma and Phaeostigma notata) plus a non-British species Raphidia ophiopsis. As the two scarcer British species are excluded you can't use this to make a certain identification.

It is extremely difficult to rear snakefly larvae. According to H Aspöck in "The Biology of Raphidoptera: a Review of Present Knowldge" published in Acta Zoologica Academiae Scientiarum Hungaricae 48 (Suppl. 2) in 2002, larvae kept at room temperature may be kept alive for several years going through up to 15 instars. However they very rarely pupate and even more rarely develop into adults with abnormalities. Perhaps pupation could be initiated by chilling?

I was examining a beetle under the microscope in my study when I saw a movement round the back of the specimen pot on the microscope plate. I was more than a little surprised to find that it was a snakefly larva! How on earth it got there I have no idea - my best guess is that it had emerged from an egg I had unknowingly brought in with me on a leaf.

Using the Norwegian key this keys to Xanthostigma xanthostigma. Given that is the commonest speices in Norfolk and the next commoneset species is ruled out by the key, that's very likely what it is, but in the absence of knowing what larvae of the two scarcer species look like I cannot confirm the identification at present.

unidentified snakefly larva, perhaps Xanthostigma xanthostigma, North Elmham (Norfolk, UK), 15th April 2023