NC State University Insect Museum

A few months ago, I wrote a post about robber flies, particularly their propensity to kill and consume vertebrates. In it I claimed that the largest robber fly in the world is the aptly named Satanas gigas. It turns out I was wrong; I had probably misheard someone say that S. gigas is the largest in Europe. Friends of the blog Dave Williams and Eric Fisher name the robber fly with the longest body length and wingspan as Microstylum magnum from Madagascar. There are ever so many bizarre insects from Madagascar. While not as fear-inspiring as Satanas gigas, M. magnum is a solid name for a giant predatory fly.

I have seen species of Microstylum from North America, and they are big insects. M. magnum is far larger than its American congenerics. It has a wingspan of up to 84 mm. In case you are having trouble visualizing the size of M. magnum, Dave Williams graciously provided several photos of the beast with a ruler and a human hand for perspective. If the relatively smaller Mallophora leschenaulti can catch and devour hummingbirds with ease, imagine the avian destruction that Microstylum magnum could wreak. I have a new theory about what drove the evolution of gigantism in elephant birds: not getting carried away by M. magnum.

The largest robber fly in terms of mass is more difficult to objectively measure. According to Dave Williams, it is probably an Australian robber fly in the genus Phellus. Here is a page with photos of, and biological information about, Phellus olgae from Brisbaneinsects.com. Its wingspan is 75 mm, but species of Phellus are more heavily bodied than Microstylum magnum. What's your favorite giant insect?