So our intrepid photographer Nancy Partlow sent us these photos and a story. She was out in her garden one day watching the pollinator animals, She was looking at the fall asters when she saw this insect. Nancy immediately got nervous and quickly put some distance between herself and the bug: this is of course of a yellow jacket wasp, right? Nancy and I both have had a childhood horror of these hornets, which is pretty ironic considering that now fifty years later we plant gardens which attract them. But even today one or the other of us will call in early spring and in a voice of doom report: “They’re baaaaaack….” The first fat yellow jacket queen of the year can still give us the chills. So it was very reasonable to me that Nancy would very quickly back off of this wasp. Except…..it’s not a wasp.
Nancy has become an acute observer of nature, and she noticed something weird about this so-called wasp. Yellow jackets make a low ominous droning hum as they explore their territory: that sound strikes terror in the hearts of children. But this insect had an annoying high pitched buzzing. Nancy said it was like the difference between a B47 and an ultralight.
The other thing she noticed was that it was pretty nervous and twitchy. Now yellow jackets are a top insect predator and they behave like they own the neighborhood. If you’ve ever tried to shoo one off of your picnic food, you know how persistent and unflappable they can be. This insect was very flighty and Nancy had a hard time getting close enough to get these pictures. That struck Nancy as pretty strange, too.
So the next picture she got really tells the tale: look at those huge alien compound eyes: no wasp has eyes like that. Look too at the short knobs of antenna: these are very unlike the antenna of wasps. And those thick hairy legs are much more typical of another insect. What we have here is a FLY, pretending to be a wasp. By putting on the coloration of a yellow jacket, other predatory insects will think twice about trying to eat it. This is what is known as a bee mimic.
It’s a great trick.
• photos by Nancy Partlow
• This fly is probably Spilomyia citima
• Megan Asche has a great blog with other photos of this insect. Check her out at:
• Bug Guide is a great ID resource: http://bugguide.net/node/view/15740