Hornet mimic...

A strange day weatherwise - hot, wet and windy - a bizarre combination! The morning was occupied by data entry, while this afternoon I tried to tackle some of the overgrown garden, which has now got seriously out of hand.

While I was outside I spotted a couple of interesting hoverflies on the marjoram flowers. This one is Volucella inanis, a large, brightly coloured species that mimics a hornet. The larvae are ectoparasites of social wasp larvae, and have been found in association with German wasps Vespula germanica and hornets Vespa crabro. They are, unlike any other member of the genus, very flattened so that they fit into the larval cells beside the wasp larvae on which they feed.

Ten years ago this species had a very restricted distribution in Britain, being found in open areas in woodland and scrub, parks and gardens, mostly in the outer suburbs of London and the surrounding countryside. It was sufficiently rare to be considered Nationally Notable.

A few years ago we started seeing this species around Peterborough, and now it's an annual visitor to the garden, mostly appearing from late July, though like many other insects, it's emergence seems to have been delayed this year and this is the first I've seen. There are now records as far north as the Humber.

There is another similar species, Volucella zonaria, which is a little larger, has more chestnut-coloured patches on the abdomen, and only has one dark spot on the yellowish wings, rather than the two of V.inanis. This is definitely somewhat scarcer around Peterborough, and retains a more strongly south-eastern distribution.