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Hornet Robberfly

Hornet Robberfly ©Cécile Bassaglia

Hornet robberfly

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Scientific name: Asilus crabroniformis
With black-and-yellow markings, the Hornet robberfly looks like its namesake, but is harmless to us. This mimicry helps to protect it from predators while it perches in the open, waiting for its own prey.

Top facts

Category

Stats

Body length: 2.5cm

Conservation status

Priority species under the UK Post-2010 Biodiversity Framework.

When to see

June to October

About

The Hornet robberfly is a predator, sitting and waiting on a suitable perch (such as a stone or pile of animal dung) for smaller insects to fly past, which it catches on the wing. It prefers dung beetles, but will also eat bees and grasshoppers. It breeds in animal dung on heathland and downland, the larvae hatching and feeding on beetle grubs in the soil.

What to look for

The Hornet robberfly has a brown thorax and a black-and-yellow abdomen, just like its namesake. There are 28 species of robberfly in the UK, which can be very difficult to tell apart; the Hornet robberfly is one of the largest.

Where to find

Southern England and South Wales.

Did you know?

The main reason for the decline in the Hornet robberfly is the transferral of harmful chemicals from the treatments farmers use on their livestock, to the dung in which the insects live. In turn, this kills, or causes serious deformities in, the robberflies that feed on the dung.