Macro Monday: Assassin fly

This is a Laphria sp.  of robber or assassin fly, showing a fine mystax, the bristly hairs on the face which are believed to help protect it from injury when it tackles its prey. They are sit-and-wait predators that attack and capture other flying insects–including bees and wasps–while in flight. They then use their dagger-like hypopharynx to penetrate into a soft area, inject enzymes, and then suck out the resulting soup of dissolved tissue.

I don’t often get the chance to photograph robber flies (Asilidae), so it was nice to have a brief opportunity to do so during a visit to Halfmoon Lake Natural Area on the 13 June, 2016. I had just returned to my feet after crouching to photograph an awkwardly positioned jumping spider when I noticed the robber fly sitting on a leaf on the other side of the path. My camera was mounted with a Canon MP-E 65mm f/2.8 macro lens, which magnifies from 1 to 5x, and is not the ideal lens for this size of an insect, which has the bulk (and fuzziness) of a bumblebee. At about 18mm long, I could not ‘fit’ this fly easily in the frame of the crop-sensor camera I was using (Canon 70D), even at the minimum magnification setting, so I opted to frame for a portrait.  I had the chance for two shots only, and the first was hopelessly out of focus. Because all the details required are not visible in this photo, an exact ID was not possible, but, at the time, (June 2016) Dr Robert Cannings believed it was probably Laphria posticata.