The hornet robber fly feeds on insects like beetles (Image by Sam Bosanquet)

The hornet robber fly, which feeds on dung beetles, has been found thriving in Castle Meadows near Abergavenny, Monmouthshire.

The fly is so rare it has been given priority status in the national Biodiversity Action Plan.

But although it looks like a hornet without the sting and it feeds on large insects like grasshoppers and beetles, it is not likely to attack a human.

Colin Titcombe discovered the fly.

"They are the largest fly in the country," he said.

We are over the moon about it Ian Smith, Monmouthshire Countryside Service

"To live they need areas which are free draining - like Castle Meadows is - and they need to have grazing animals like cattle and horses for the dung.

"The fly is very rare but there is a strong population here," he added.

Thrilled

Described as being about 2.5 centimetres long, the fly has seen its numbers decline rapidly in recent years.

Blame has been put on the use of internal pesticides given to cattle which affects the manure they produce, making it abhorrent to the fly and its prey, dung beetles.

Local experts believe the answer to why the fly is flourishing in the meadow is down to the way the land is managed through grazing.

Ian Smith who is the head warden at Monmouthshire Countryside Service said he was thrilled that the fly had been discovered at the site.