Female wolf spiders make for discerning mates. If they aren’t satisfied by the end of sex, they eat their partners alive.
That might explain – tangentially – why Matthew Persons, an American biology professor, kept finding the poisonous spiders having threesomes in his garden.
“By the third time I saw it, it’s like, “I’ve got to take detailed study of this,” the Susquehanna University professor told Live Science.
After months of research, Persons’ study is now set to be published in the Journal of Arachnology. He explained to HuffPost UK the thinking behind it.
There are a few reasons why male wolf spiders might enter into an arachnid menage-a-trois, Persons explains.
“Waiting until a female is already pre-occupied allows the second male to avoid being cannibalised,” Persons says, adding that it reduces the risk of a fight with another male too.
It helps that the female wolf spiders have paired reproductive openings; the males also have two copulatory organs.
“When solo, the male inserts one pedipalp into one and then the female swivels her abdomen and then the male inserts the other pedipalp into her other opening,” Persons says.
“But when I observed two males mating simultaneously, each male spent most of the time on one side or the other and inseminated only from that side.”
However, that’s not the only incentive for the spiders to have threesomes.
“Courtship is energetically costly and attracts predators, so this is an interesting way to avoid those costs,” Persons says.
Some sessions last up to four hours.
“Males that perhaps can’t court as intensively or can’t otherwise compete with another male, might be able to get matings this way too. In other words, they parasitize the courtship displays of other males,” he adds.
Glad we’ve got that cleared up.