Female dragonflies fake their own deaths to avoid males from bothering them for sex, they do that by falling from the sky and lying motionless on the ground until the males go away.
A zoologist from the University of Zurich known as Rassim Khelifa, conducted a study as the first time scientists showing that odonates feign death as a tactic to avoid mating, and a rare instance of animals faking their own deaths for this purpose. Odonates is the order of carnivorous insects that includes dragonflies and damselflies.
The zoologist had been collecting the eggs of odonates in the Swiss Alps for experiments into how temperature affects larvae. But over the two summers he spent there, he noticed unusual behavior among female dragonflies of the species Aeshna juncea .
Khelifa wrote in a study published in the journal Ecology, that on July 5, 2015 while he was waiting at a pond near Arosa, at about 2,000 meter elevation, he witnessed a dragonﬂy dive to the ground while being pursued by another dragonﬂy, the individual that crashed was a female, and that she was lying motionless and upside down on the ground.
The upside-down posture is abnormal for a dragonﬂy. The male hovered above the female for a couple seconds and then left. Khelifa expected that the female could be unconscious or even dead after her crash landing, but she surprised him by ﬂying away quickly as he approached.
That’s when Khelifa noticed that the female dragonfly had just tricked the male by faking death to avoid male harassment. The zoologist became the ﬁrst one to record sexual death feigning in odonates. Khelifa pointed out that there are few instances of animals faking their own deaths, with four others known to science. These include two species of robber fly, the European mantis and the spider species Pisaura mirabilis, where the males fake death in order to avoid being killed after mating
Khelifa decided to document dozens of cases where females would crash land and play dead while being pursued by a male. He also looked at the reproductive behaviour of A. juncea to try to work out why females would do this.
He observed that females would arrive at the ponds where the males were waiting to mate. Males would intercept females mid-air before copulating somewhere nearby. The male then flew away and the female laid eggs on her own, without any protection, unlike many other dragonfly species, where the male will guard the female.
Khelifa also observed that the more male competition there was, the more likely female dragonflies were to fake their own deaths. Around 86 percent of the cases saw females crashing to the ground.