Jul 11 2011
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.