Everyone knows butterflies and dragonflies but mantis-flies are strange little creatures barely known even to most people interested in insects. How do I know that? Well, I count myself as “interested in insects” and I didn’t know of their existence until about a year ago – but one solitary person is far too small a population sample to draw conclusions from, of course, so let’s go to the online Field Guide to the Insects of Australia, with 640 members: out of their 24,600 photos, only 50 are of mantis-flies (you can see them all here). Jean Hort’s red one attracted quite a buzz of excited comment.
Mantis-flies (Mantispidae), also known as mantidflies, have nothing much to do with flies (Diptera) or, for that matter, dragonflies or butterflies. Their nearest cousins are actually lacewings and ant-lions, grouped with them in Neuroptera. All neuropterans are predators and have two pairs of wings.
Their next-nearest relations are beetles, although you certainly wouldn’t think so from looking at them – “little mantis” must be by far the most common first guess. The amazing similarity of the grasping forelegs is a result of convergent evolution, not of kinship: like the mantis, the mantis-fly lurks in the foliage and lashes out to capture unwary smaller insects.
Graeme Cocks says there are 45 Australian species of mantis-flies and he has recorded seven in our region. The only two I have ever seen, last week’s discovery (above) and the one I posted here nearly a year ago, represent two of his seven species. They are not very big – only 10 to 15mm long – so they are easily mistaken for a small wasp or a juvenile mantis, or overlooked altogether. Careful observation pays off!