Friday, April 28, 2017

"Female dragonflies fake sudden death to avoid male advances"

Rassim Khelifa from the University of Zurich, Switzerland, witnessed the behaviour for the first time in the moorland hawker dragonfly (Aeshna juncea). While collecting their larvae in the Swiss Alps, he watched a female crash-dive to the ground while being pursued by a male.

The female then lay motionless on her back. Her suitor soon flew away, and the female took off once the coast was clear.

“I was surprised,” says Khelifa, who had never previously seen this in 10 years of studying dragonflies.

Female moorland hawkers are vulnerable to harassment when they lay their eggs since, unlike some other dragonflies, they aren’t guarded by their male mates. A single sexual encounter with another male is enough to fertilise all eggs and copulating again could damage their reproductive tract.

Khelifa found that the females often retreat to dense vegetation near ponds at this time, probably to hide. And they often act dramatically when they emerge.