Monday, November 29, 2010

Reminiscing about robbers

Robber flies, that is.

Every year brings something new to my proverbial radar. New birds to learn, both by sight and by ear. New butterflies to learn.  New flowers to learn. New dragons and damsels to learn. And new flies. I was vaguely aware of robber flies before this summer, mainly because I had read about them on a the very educational blog of a fellow Ohioan.  Still, reading is one thing. It doesn't replace the feeling of experiencing these creatures for yourself. This summer I had the luck to be able to examine a couple of them at close range.

Quoting from the Kaufman Field Guide to Insects of North America: "[Robber flies] are to other insects what falcons are to other birds: swift predators on the wing."  They are usually distinguished by their "bearded" face, and also by the fact that the top of their heads is concave between the eyes.

A Robber Fly, most likely belonging to the genus Promachus, or the Giant Robber Flies. Promachus is translated from the Greek as "who leads in battle."

This robber caught my eye because it was darting about. When I first saw it I thought maybe it was a dragonfly based on its size, but I knew it wasn't flying right to be a dragonfly. Closer inspection ensued when it landed on the leg of our patio table, where it remained for some time. At this time I was able to make the positive ID. It was tame for a flying insect, and stayed in place despite the fact that my camera lens came within inches of it. It was, undoubtedly, scanning the air around it for a potential meal, and was either too preoccupied to care or simply didn't feel threatened by me or my camera. Interestingly, a small bug (I can't remember what kind at this point) landed and walked right past it, and the robber didn't budge. I'm not sure if it considered the other bug an inferior meal, of if it just didn't see it all.

In these images you can get a better look at the characteristic "beard."

I sat with this fly for probably close to 10 minutes, but never got to observe it hunting. I went in the house for a bit, and when I came back it was gone. Maybe next year, if I'm lucky, I'll get to watch the hunting process.

I came across another robber a few weeks later, but this one was dead. I found it in Dave's truck, and it was MUCH smaller than the one I found on the patio table. Suffice it to say they come in a variety of sizes. The one pictured above was easily as long as my index finger. This other robber was about the size of the first joint of my thumb (from tip to knuckle).

Itty bitty Robber Fly

Compared to my finger tips, you can see how small this robber is

With winter less than a month away, the only insects I have to keep me occupied currently are the poor half-dead flies buzzing around the windows in our house, and the occasional spider in a corner. I won't be seeing anything like this again until next summer, I reckon. Yet another reason for me to prefer the warm months over the cold ones.

Until we meet again, robber...


Kelly said...

...interesting info...and great photos too!! Rick just told me snow might fly this weekend. I guess winter really is coming...

Anonymous said...

Such serious flies! I'd be cautious with them - do they bite? Their look - especially their colors look interesting. I wish I could see one in motion.

Heather said...

Aluajala - I don't think these flies are interested in humans, just other insects. Good for us, right? The flight pattern of this fly wasn't what caught my eye so much as the size of it - if had seen the smaller one flying, I might not have paid much attention to it. Regardless, they are very interesting creatures.

Lisa Sells said...

Hi! I just LOVE your blog! And I love it that you also crawl around on the ground to get a better vantage point of whatever critter happens to catch your interest! We have so much in common-I will enjoy following your interesting writings and beautiful photos!

KaHolly said...

Heather, those are some amazing macros of that fly. Love it when I learn new things. Great post.