I recently read an excellent post by Julia Craves over at Urban Dragon Hunters about the dangers of using images on the internet to identify insects so I’m being more than a little cautious about my identification of this large fly.

Here’s what I do know (or at least I think I do). I feel reasonably confident that this is a tachinid fly, a member of the particularly interesting family Tachinidae. Female tachinids lay their eggs on (or in) host invertebrates or on the food plants of host invertebrates. One way or another, once the eggs hatch the larva feeds on the host and eventually it dies. Very cool (if you’re not a host).

I watched this large, black fly bumbling around in the asters along with the hover flies that were feeding on the nectar. It seemed rather clumsy as it moved from flower to flower,  but it was definitely wary. I had to move slowly in order to get close enough to get a good photograph and even then a lot of waiting was involved.

I think this tachinid fly is Tachina algens – there isn’t a reference to this species on BugGuide.Net but there are several very similar photographs (remember that warning about basing an identification on images found on the internet?) that reference simply Tachina sp. G.G.E. Scudder and R.A. Cannings refer to a tachinid species in the UBC Zoology Department web page Diptera Family of British Columbia saying:

Tachina algens Wiedemann is a particularly common BC representative of the genus Tachina; it is black with yellow wingbases and dense yellow setulae behind the head.

That’s a pretty good description of this fly. It’s a black, bristly fly with a distinctive yellowish looking head and yellow wingbases. I’d love to get this fly conclusively identified so if you can help confirm it, write me a comment below.

Once again, I’m always amazed by the backyard diversity you can find in your garden even in a suburban environment. I’d never seen one of these flies before but I’ll definitely be looking for more of them!