Sunday, June 18, 2006

Ctenophora nigricornis - an unusual cranefly

One of the more spectacular insects I have seen this year in Brede High Woods is this cranefly that fancies itself as an ichneumon.

Ctenophora nigricornis is a Red Data Book species that breeds in dead timber in ancient woodland and, although widespread in Britain, there have been very few recent records. In East Sussex the only other sighting is from St. Dunstan's Farm near Rushlake Green. The horn-shaped ovipositor is for penetrating dead wood.

A curious thing about these and some other flies is why they look somewhat like ichneumon wasps. So far as I know, icheumon wasps are not especially distasteful and the only thing they sting is their host when they lay an egg, so is it a defence strategy, or just an effective camouflage? The irregular red and black patterns may look like dappled sunshine and shade, though the insect in this picture was very obvious as it stood four square on a leaf.

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