Female Pine Snakefly Alantoraphidia maculicollis at Aigas Field Centre Scotland, 4 July 2024 (Photo © Martin Kincaid)
At the Summer Review meeting on 3 September, our first evening back at the Cruck Barn this autumn, Martin Kincaid showed a photo of a Snakefly he had seen while away in Scotland. Locally, these insects are not recorded often but one has been recorded from Little Linford Wood and Tim Arnold has had one ‘come to light’ when he has been moth-trapping.
These are strange-looking insects with two pairs of long oval overlapping wings that are translucent but with slender and intricate black veins, rather like the shape of wing of Lacewings. The wings extend well beyond the body and the female has a long slender ovipositor (egg-laying tube) extending even further back than the wings. At the front, the Snakefly has a very long black pronotum (prothorax) with a head that can rear up, looking like a miniature cobra ready to strike.
They have a four-stage life cycle of: eggs, larvae, pupae, adult (‘holometabolous’). The adults are active in the day, mainly in woodland, are significant predators of aphids and mites and their larvae are also carnivorous. The adults are food for woodland birds such as treecreeper, great spotted woodpecker, wood warbler, and nuthatch.
Snakeflies are not Flies (Diptera): they are in a separate Order called Raphidioptera (rahpis = needle. pteron = wing). Species recognisable as from the origins of this Order appeared during the Early Jurassic (201-145 million years ago) and were most diverse during the Cretaceous (145 to 66 million years ago) since when they have declined considerably.
There are four (and a possible fifth) Snakefly species in Britain. Three of these are south of the Scottish Border: Oak Snakefly Phaeostigma notata, Small Snakefly Xanthostigma xanthostigma, and Scarce Snakefly Subilla confinis. One, the Pine Snakefly Alantoraphidia maculicollis is in Scotland and in southern England & Wales. The possible fifth species, Raphidia ophiopsis occurs widely in Fenno-Scandinavia and Central Europe so may yet be found in Scotland. The Oak Snakefly is the largest of the British species with a body length of 10-15mm and wingspan of 20-30mm; the smallest is the Small Snakefly with a body length of 7-9mm.
There are photos of all four species of Snakefly in Paul Brock’s field guide ‘Britain’s Insects: A field guide to the insects of Great Britain and Ireland’ (Princeton University Press: WildGuides 2021). That book is worth every pound for 608 pages at £25, but mostly at under £20: it covers 1,653 species of insect of the 24,000 British insects but is about the best-illustrated field guide you can get in a single volume and will cover most of what you are likely to see.
Peter Barnard, a member of the Royal Entomological Society, has written about Snakeflies that ‘Adults are not often seen as they spend much of their time high in the tree canopy; newly emerged specimens can be found at lower levels, and the females descend to oviposit, but otherwise any snakeflies seen by the casual observer have probably been dislodged from the canopy by strong winds.’ (Peter Barnard, RES Book of British Insects, 2011, p.317).
In Milton Keynes we are in the area for the largest of these species, which is the Oak Snakefly, and the smallest, the Small Snakefly which inhabits Oak woodland. There is a record of Oak Snakefly Phaostigma notata on the National Biodiversity Network website map at Little Linford Wood and another north of Finmere Wood between Romer and Balmore Woods. Could they also be in Linford Wood and Howe Park Wood?
There is a useful online guide to ‘Lacewings and Allies’ by James E Jepson that covers Snakeflies:
https://www.northwestinvertebrates.org.uk/wp-content/uploads/2023/11/Lacewing-and-Allies-Part-1.pdf
Mike LeRoy
6 September 2024