Small Robber Fly

2015 November 11

Rosie caught this little robber fly for me on June 18, 2015.

It was fairly lethargic, and was willing to perch on my fingertip for photographs.

While that last picture makes it appear that it was looking alertly at the camera, it actually seemed to have a crick in its neck and always held its head cocked off to its right.

When I first started trying to get pictures, I forgot that I’d been using the camera for non-macro photography, and the aperture was set way too wide at first. This produced a lot of blurry pictures. But, here’s one that at least had one eye pretty well focused.

Anyway, normally robber flies don’t stay still for pictures very well, which is why I don’t have a lot of pictures of them. I suspect that this one might have been having trouble flying due to neck damage.

It looks a lot like the robber flies in the genus Dioctria. In fact, it could be a male Dioctria hyalipennis (the females would have a more bulging abdomen, with most of the bulge near the tip). Poking around a bit more, I see that D. hyalipennis is one of two robber fly species that came over from Europe, and is slightly invasive. And, after all the times we have seen that the dominant species up here in the UP tend to be the invasive non-natives, I’d say that this ID is looking more likely all the time.

Robber flies are pretty fierce predators, chasing down and eating other flying insects kind of the same way that dragonflies do. Their body and wing shape are broadly similar to those of dragonflies, which kind of suggests that this shape (long, thin wings and an elongated body) is very good for pursuing other flying objects.

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