Sunday, July 25, 2010


This is Tachina grossa, one of the largest and possibly the ugliest fly in Britain. It's as large as a bumblebee and spends its days feeding on nectar - harmless enough, unless you happen to be the caterpillar of a butterfly or a moth - in which case, like many other species of tachinid, it will lay its eggs on you. Its larvae burrow through their host's body wall and slowly consume it from the inside. Gross.

Apparently, T.grossa has a particular penchant for large caterpillars - especially those of the oak eggar moth and fox moth

This specimen was spending a sunny afternoon on a hillside at Stanhope in County Durham, feeding on marjoram flowers.


  1. Superb photographs, it is an ugly blighter and going bald too, not that I'm in any position to criticize it for the latter or possibly the former.

  2. It certainly lives up to its name!
    Cracking shots though Phil, especially that second one.
    Never seen one of these before. I'd certainly remember it lol

  3. Hi Adrian, it was probably the ugliest fly I've ever see -although its fellow flies might think differently..

  4. First time I've seen one too Keith - at first sight I thought it was a bee

  5. Thanks Phil! I photographed one of these recently feeding on a hogweed flower. I've been trying to find out what it was and then I stumbled across your site. Isn't technology great ... some of the time :-)