Friday, August 26, 2011

Almost UFO's

I call these almost UFO’s because I know what they are and some people could probably figure it out from the photo. The yard was aswarm with dragonflies grabbing ascending winged ants rising from the lawn and I was futilely trying to capture the event. Even if I did get a clear image, it’s impossible to capture the beauty of a dragonfly swarm glittering in the setting sun.

The dragonflies were quick to take advantage of the ant exodus. The departure of reproductive individuals from an ant colony is a short duration event. More ants in the air means fewer total victims of predation. The timing also makes it less likely that predators will be able to accumulate in large numbers quickly enough to be a major threat to the ants. I observed both queen ants and the smaller males heading into the air. From what I could see, the dragonflies targeted the queens. Queen ants must be packed with nutrients because I’ve never seen a predator pass up a queen.

The dragonflies all appeared to be Common Green Darners. As the days shorten, dragonfly swarms will become increasingly common. This was a small swarm of around a dozen individuals. I’ve seen September swarms that contained hundreds of dragonflies.

By the time I turned my attention to the ants, the queens had all departed. The males were still launching at a fairly steady rate.

The males will catch up to the females and mate in the air. Other colonies of the same species are probably launching at the same time. As I watched, the workers and remaining males suddenly headed down the grass stalks and returned underground. There’s a good chance that they’ll be back at it tomorrow evening.


  1. Hi, Lois. At the rate they were eating, I got the impression that an ant was only a two bite item.