A new study found that female dragonflies play dead to avoid having sex with males. When female dragonflies mate, they want to lay their eggs and be left alone, so when they are “stalked” by an unwelcome male, they fake their dead so that he would leave.

After the male stalkers leave them, the female dragonflies fly off, according to the research published April 24 in the journal Ecology.

A new study found that female dragonflies play dead to avoid having sex with males. Image credit: The Flying Kiwi
A new study found that female dragonflies play dead to avoid having sex with males. Image credit: The Flying Kiwi

Rassim Khelifa, a Ph.D. student in the Department of Evolutionary Biology and Environmental Studies at the University of Zurich, discovered the phenomenon in 2015 when he was conducting research in the Swiss Alps.

Female dragonflies ‘feign’ deaths to avoid aggressive males

Khelifa traveled to the Swiss Alps in 2015 to collect eggs of the moorland hawker dragonfly, as he was studying the effects of climate change on the animal by exposing larvae hatched from their eggs to varying temperatures back in his laboratory. Khelifa spent so much time by the pools watching female dragonflies and looking for eggs that he noticed their odd behavior when a male approached them.

“It was a byproduct of my research,” said Khelifa, according to Live Science.

In his research, Khelifa explained that he noticed the females first strategy to go unnoticed to the males was to choose an egg-laying place that is concealed by plants. However, the males can still chase them on their way to and from the site, and that’s when the females pretend they are death.

Called sexual death feigning, the behavior developed to guard females against aggressive males, and female moorland hawker dragonflies sometimes risk injury and death if they are forced into mating. Mating time for moorland hawker dragonflies occurs in summer, and the males line up near ponds, waiting to catch a female to mate with.

The females arrive the males fly towards them to find a mating partner, and when a male succeeds, the couple forms a copulatory wheel, suing vegetation for support. Once the females mate, the male leaves immediately and she lays her eggs. However, as she tries to leave, other males stalk her and jump on her to mate again, and that’s when she stages her death.

When female dragonflies mate, they want to lay their eggs and be left alone. Image credit: Bythedrop.com
When female dragonflies mate, they want to lay their eggs and be left alone. Image credit: Bythedrop.com

“In a lot of dragonflies, males try to seize the female with or without their consent,” said Khelifa, according to National Geographic. “The fittest -that is the fastest, most powerful male- is usually the one who mates.”

Khelifa observed 35 female dragonflies and found that 27 crashed to the ground or into shrubs when a male approached them, faking their own death, and of those 27, 21 succeeded in tricking the male stalkers. The researcher also noticed that about 71 percent of those females that crashed preferred dense vegetation to open ground as their stage to feign their deaths.

Male dragonflies rely on movement and color to detect females, so it was impossible for them to spot them when they laid frozen dead in the ground or hidden in the grass. Khelifa noted that female dragonflies that kept on flying were caught by the males midflight. The death-staging females were so fully aware of their surroundings, Khelifa wrote that when he tried to catch them, 87 percent of them were able to get away.

Other dragonflies also prey on females to mate with them

Dragonflies have odd mating rituals, others in which the male aggressively attacks the female to mate. Some males jump on unwary females when they are standing still;¬†others, called “stealers,” attempt to split mating pairs by attacking them. Other species, known as “water lurkers,” grab the females when they are laying eggs, so they can mate with them without their consent, even if it means that she’ll drown in the process. Female dragonflies have developed defense mechanism against aggressive males, including flying away at high speed, submerging into the water, and even fighting back. Khelifa noted that there are only five species known to practice sexual death feigning, including a praying mantis and a spider.

Staging their own deaths is a strategy used by many animals to evade predators. According to Khelifa, the moorland hawker female dragonflies use the same approach to avoid sexual conflict and confrontation with males. He believes that the behavior evolved into the death feigning for several reasons. In the sites he worked looking for dragonflies, the noticed that males outnumbered the females, which he believes happens because the females are trying to get away as possible from their counterparts. Sexual death feigning can also protect them against the many males that stalk them during mating season.

Source: National Geographic