The Hornet Robberfly

The Hornet Robberfly is the largest fly in Britain

The Hornet Robberfly, Britain’s largest fly has been found on National Trust land in South Devon.

The discovery of the Hornet Robberfly on National Trust land

The Hornet Robberfly (Asilus Crabroniformis) has been found on the National Trust farm at East Soar. The Hornet was discovered by local entomologists and has not been recorded on the site since sometime before 2000. The fly, Britains largest predatory species, is nationally scarce and rapidly declining due to loss of habitat and a lack of grazing in coastal areas.

Improvements in coastal habitats see the return of the Hornet Robberfly

Rob Wolton made the discovery while surveying the area with a Devon Fly Group and explained:  'We were both surprised and delighted to find this spectacular fly on National Trust land near Bolt Head.'  Completely harmless to people, the adults are fearsome predators of grasshoppers and large beetles. 

‘Once fairly common across southern England, over recent decades its numbers have fallen dramatically so it is now a high conservation priority. Its larvae feed on beetle grubs in cow pats on rough pastures, so light grazing with cattle is essential for the fly's survival.

‘Equally important, the cattle must not have been treated with wormers that render their dung sterile. I congratulate the National Trust for achieving just these conditions, he added.’

Emma Reece, Area Ranger with the National Trust, was very excited by the discovery:  ‘The farm is in a stewardship agreement with Natural England, and a lot of work has been carried out by the Trust and our tenants over the last 4 years to improve the condition of the coastal area for the benefit of a wide range of wildlife. We are really pleased to see discoveries like the Hornet Robberfly which would not survive without the right grazing conditions.’