Have you ever had a cloud of bugs fly around your head, yet when you wave them away they’re back in an instant?  The bugs aren’t biting but they will not leave.  What’s going on?

It’s a mating ritual.

In some insect species the winged adults congregate in a swarm to meet each other.  It’s the bug version of the bar scene.

Each bug flies around in the crowd, looking for a member of the opposite sex.  The individuals break away to go off and mate yet the cloud stays put.  To do this they use a tall object as a reference point — a swarm marker — to maintain their position.  We see this in the fall with flying ants at hawk watches.  The mountain is their marker.

Anything can be a swarm marker.  In early June, thousands of mayflies swarm at Lake Erie in Cleveland using buildings, people and trees as their markers.  They look scary but they’re harmless — and messy when they leave the swarm to mate on windows, walls, cars … everything!

So it’s not that the bugs love you.  It’s just that they’re using your head as a swarm marker.  Walk under a tree with low branches and they’ll leave your head to use the tree.  Good luck leaving them behind when you walk away.

Of course, this doesn’t work with mosquitoes.  Mosquitoes do love you!

(photo by Anton Gvozdikov/Shutterstock.com)

p.s. For more information about midge swarms, see page 9 of this document from Nature.org.

5 thoughts on “Swarms

  1. LOL about “bug version of the bar scene!”

    This is great info! I already learned something and the day is still young!

    I like the part where you say how to get rid of the swarm! Good to know!

  2. Marianne..I was going to say exactly the same thing about the “bar scene”! Kate, that was really good. Also the fact that mosquitoes *do* love us. Thanks for the info.

  3. Well, that makes me feel better about being engulfed in the moving clouds of insects….at least it’s not me they’re interested in. Although it *is* me if they are mosquitoes….I am a mosquito magnet. I’ve finally started wearing OFF! in the woods because I can’t stand it anymore.

  4. Fascinating! One of the downsides to being a tall person perhaps. What’s really terrible is when you are on your bike and you see one when it is too late to swerve. Nothing like coasting through one at about 15 mph. Blech!

  5. The mayflies also use light poles — go down to Waterworks parking lot sometime in the late spring and look up — there are zillions of them! I once drove home and discovered a mating pair still on my car — they must have ridden all the way home on my trunk. About 9 miles!

Leave a Reply

Your email address will not be published.