Do Female Praying Mantises Really Eat Their Mates?
Quick Answer
Do female praying mantises eat their mates? Sometimes, not always. In species where sexual cannibalism occurs, it happens in roughly 13 to 28 percent of natural encounters in the field. Hunger is the main driver: starved females cannibalize at much higher rates than well-fed ones. Males are not passive about it. A 2021 study of springbok mantises found males initiate a physical struggle, and in 27 percent of cases the male wounded the female with his foreleg claws. Females that do eat the male lay around 51 more eggs.
In 1886 an entomologist named Leland Ossian Howard published a short note in Science describing a female praying mantis eating a male who was trying to get away. That one account did a hundred and forty years of work. It became the fact everybody knows, and it is wrong in both directions.
Thirteen to twenty-eight percent
She does not always do it. Across mantis species that practice sexual cannibalism at all, the rate in natural field encounters runs somewhere between 13 and 28 percent. A 1992 field study of Mantis religiosa in the wild put cannibalism at 31 percent of observed matings, which is the high end but nowhere near universal.
Hunger is the lever. A 1994 lab experiment found well-fed females did not eat their mates at all, while starved females ate them in every case but one. Barry and colleagues found the same pattern in 2008: females in poor body condition were far more likely to cannibalize. She is not performing a ritual. She is deciding whether she needs the calories.
Males appear to read this. A 2006 study by Lelito and Brown found males approached hungrier females less often, and when they did approach, they did it more carefully.
The correction is also wrong
Somewhere around 2010 the internet learned that the mantis thing was overblown, and the correction went too far. You still see it: the claim that sexual cannibalism is basically a laboratory artifact, produced by starving insects under bright lights in small boxes while scientists watched.
Some of the early work was genuinely bad. Roeder's experiments in the 1930s and 1950s used small containers and large predatory insects, and the conditions were nothing like a field. But the field studies went out and looked, and cannibalism was still there. Lawrence found it in roughly a third of wild matings in Portugal. The behavior is real. It is just conditional.
Both versions of the story get told because both are tidier than the truth, which is that she does it about a quarter of the time and whether she does depends mostly on how recently she ate.
He fights back, and he wins sometimes
Nathan Burke and Gregory Holwell watched 52 pairs of springbok mantises in the lab for 24 hours each and published the results in Biology Letters in 2021. The findings are not what the myth describes at all.
Physical contact happened in 56 percent of pairings. Every single time, the male started it. Ninety percent of those contacts turned into an outright struggle. Of the males who grabbed the female first, 58 percent went on to mate successfully, though half of those were eaten afterward anyway. In 35 percent of pairings the female won the opening fight and ate him.
Here is the part nobody puts in the nature documentary. In 27 percent of cases where the female lost the struggle, the male injured her with his foretibial claws, causing severe puncture wounds to her abdomen.
Males who both mated and survived were overwhelmingly the ones who had fought. The springbok mantis male is not an offering. He is a smaller animal who jumps a bigger one and sometimes stabs her.
Fifty-one extra eggs
Kate Barry at Macquarie University worked out what the male is worth as food. Her team fed crickets carrying radioactive labels to Chinese mantises, which made every atom traceable, then let half the mated pairs proceed to cannibalism and interrupted the other half.
Females that ate the male ended up with about 17.7 percent more of his biological material in their reproductive tissue. They laid an average of 51 more eggs, up to 25 percent more than a normal clutch. The work ran in Proceedings of the Royal Society B in 2016.
A male who gets eaten is not simply losing. He is converted directly into more of his own offspring, which is why biologists call it terminal reproductive effort. Whether that counts as a good outcome for him depends on whether you are asking him or his genes.
She does not need him at all
The springbok mantis is a facultative parthenogen. Females can produce viable eggs with no male involved, and Walker and Holwell found the egg cases came out the same weight either way.
Which changes what the cannibalism is doing. In this species it is exclusively precopulatory. She eats him before mating, not after, at a rate around 62 percent. That makes no sense as a nuptial gift and perfect sense as hunting. A male walks up, she is not obligated to breed with him to reproduce, and he is roughly the right size.
Walker and Holwell found age was the best predictor. Older females were less aggressive and more likely to mate. The young ones just eat him.
Why she got the reputation and the spider did too
Mantises are not the only arthropod with a public relations problem. The black widow got named for the same behavior, and arachnophobia has its own invented history stacked on top of actual spider behavior.
Howard's 1886 note landed in a culture already primed for it. The Victorians were in the middle of a long panic about female poisoners, which had its own publishing industry. A bug that eats her husband was going to be a hit no matter what the numbers said.
The numbers say she does it about a quarter of the time, usually when she is hungry, usually to a male who tackled her first.
We put her on a shirt. Girls Will Be Girls runs with I Choose Violence, and the rest of the Feminist Rage collection is for the other things people call hysterical when a woman does them.
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Frequently Asked Questions
Do female praying mantises always eat their mates?
No. In species where it happens at all, sexual cannibalism occurs in roughly 13 to 28 percent of natural field encounters. A 1992 field study of Mantis religiosa recorded it in about 31 percent of wild matings, which sits at the top of that range. The majority of matings end with the male walking away.
Why do praying mantises eat their mates?
Mostly hunger. Starved females cannibalize at dramatically higher rates than well-fed ones, and females in poor body condition are more likely to do it. There is a reproductive payoff too: Kate Barry's team at Macquarie University traced radiolabelled nutrients and found cannibalistic Chinese mantis females laid about 51 more eggs than females whose mating was interrupted, up to 25 percent more than a typical clutch.
Does the female bite the male's head off during mating?
Sometimes, and it is where the whole reputation comes from. Leland Ossian Howard's 1886 note in Science described exactly that and the image never left. Decapitation is one form sexual cannibalism takes, not a required step, and most matings do not involve it.
Can a male praying mantis escape?
Often, and he fights for it. A 2021 study of springbok mantises in Biology Letters found males initiated every physical contact, 90 percent of those escalated into a struggle, and 58 percent of males who grabbed the female first managed to mate. Males who survived and mated were overwhelmingly the ones who had fought rather than approached carefully.
Do male praying mantises ever hurt the female?
Yes. In the same 2021 springbok mantis study, 27 percent of females that lost the struggle were wounded by the male's foretibial claws, with severe puncture injuries to the abdomen.
Is praying mantis cannibalism just a laboratory myth?
No, though some early research deserved the criticism it got. Experiments from the 1930s and 1950s used cramped containers and unnatural conditions. When researchers went into the field, the behavior was still there, at lower and more variable rates. Both the "she always does it" story and the "it never really happens" correction are wrong.
