September 21, 2011

Last week (before it got so chilly here in Columbia County, NY) Liz and I were sitting on the deck watching the sunset when we saw this swarm of gnats (pronounced NATS - silent "g". They are small, two-winged flies).

Click Ghost of Gnats to see the video. 

They were all moving, but as one big, spherical shape. I suspected it was a mating swarm, so I decided to do a little reading and check it out.

Turns out it was indeed a mating swarm. When this happens, a big group of male flies are irresistibly attracted to pheromones secreted by a female or females who are ready for mating.  Pheromones (pronounced FAIR-uh-moans) are a chemical substance given off by some animals, especially insects, that influences the behavior of other animals of the same species. The males detected the pheromones from hundreds of yards away, and all rushed to the same place to try to find the female.

You end up with this ball of almost all male flies, searching for the female who is somewhere in the middle. The expression for this is "a ghost of gnats." Isn’t that great? It does look a little bit like a ghost haunting in the sunset twilight, as all the gnats move as a big group. 


Photo: A Fungus gnat, courtesy

Posted by: Seymour Simon

(1) Comments  •   Labels: Video, Insects, Halloween   •  Permalink (link to this article)   •  Share: