by Celia Bowers and Ji-In Friess
“Take Him Out” Is Usually Either a Meal, a Date, or a Murder. But the Chinese Mantis Gets All Three
Dating may be hard, but at least you’re not a male Chinese mantis. The Chinese mantis (Tenodera aridifolia sinensis) is a species native to South and Southeastern Asia. But they’re not an uncommon sight in Pennsylvania, having been accidentally introduced at a plant nursery near Philadelphia in 1896. Now you can find the slender, brown-and-green predators in much of the East Coast, anywhere from the forests out in rural nature to the shrubbery behind your house.
They’re the largest species of praying mantis found in North America and are voracious hunters, aided by those spiked forelimbs that make them appear to be in prayer. But perhaps what Chinese mantises, and mantises as a whole, are best known for is their behavioral habit of sexual cannibalism, which is just as alarming as it sounds. Sexual cannibalism is, simply put, eating one’s partner at some point in the mating process.
On a regular day, Chinese mantises may feed on other insects, spiders, grasshoppers, small reptiles, amphibians, and even hummingbirds. But when mating season comes around, the females often set their sights on a new sort of prey: their partner. In the animal kingdom, there are several different types of cannibalism, from eating one’s own offspring to preying on smaller members of the same species. What’s most curious about these mantises is that they participate only in sexual cannibalism, or the consumption of one’s mating partner, and are not observed to eat their fellow Chinese mantises in any other context. But why, you may ask, eat members of your species at all?
Well, for the female, eating her suitors is simply the optimal choice. Studies have shown that female mantises who cannibalize their partners lay up to 25% more eggs and have bigger egg sacs, or ootheca. A significant portion of the nutrients and amino acids from the male goes straight to making the eggs. Female Chinese Mantises are also significantly larger than males, which makes cannibalism not only smart but very easy
They’re much more likely to eat their mates if they’re hungry, and considering the food scarcity that mantises often face, hunger is a distinct possibility. Male populations tend to outnumber that of the females before the breeding season, but the situation is totally reversed once mating has ended. The usual estimate is that around 30% of males are eaten, though one study found that sexual cannibalism occurs in up to 50% of mantis matings. For the males, their likelihood of getting through the courtship dwindles to a coin-flip.
On the male’s side of things, negotiations are more a delicate matter. Unlike other arthropod species that practice sexual cannibalism, male mantises aren’t always eaten. They’re able to reproduce with multiple females in their lifetimes, which is at odds with males in certain species of spiders, which can’t mate more than once in the breeding season. So if the spiders get eaten by their mate to help their offspring grow, it’s not as much of a shame. Mantis males have a lot more to lose. So what can they do to avoid the fate of decapitation? A couple of things, actually.
Firstly, a male Chinese Mantis may seek out the partnership of a larger, fatter female. This way, the female is more likely to be too well-fed to eat him, and more fertile to boot. Once he selects the female, the male may switch up his approach, courtship, and copulating behaviors to be slower, performing some form of risk assessment on the female. Before courting her, it is best to figure out just how hungry she is. This is good dating advice for any species. Some males will even “sneak up” on the female and begin courtship and copulation from behind. Usually, the mantids approach from the front to start courting, but this risky technique gives the female time to contemplate just how suitable this male is as a partner or as a meal. For a good number of males, it doesn’t matter; they still find themselves headless, and the female finds herself to be very full. A helpful husband, indeed.
This is truly interesting how this type of cannibalism is so specific in regards to who is being preyed upon and when it happens. This blog did not fail to answer any questions I had along the way- for example, I was wondering how males could avoid such a fate, and sure enough my question was answered! I do have one question- Does the benefits provided to the eggs apply only when the female eats the male she mated with, or any sexually active male? I am so intrigued and plan to read into this more.
I found it so interesting that these Chinese Mantis’ only participate in cannibalism during a specific time of year. When I read the facts about females who eat their male mates lay more eggs and have bigger egg sacs, it makes sense as to why they do this. It will give their offspring a better chance of survival. I also found it interesting that males search for females who are less likely to eat them! Those that look well-fed.
I was very surprised to learn that Chinese Mantises participate in sexual cannibalism. It’s crazy to think that some species eat their own kind, considering most would want to preserve their kind and eat something else. It’s so interesting that females who eat their partners lay up to 25% more eggs and have bigger egg sacs, so in this case I guess it makes sense to eat your mating partner if it’s better for your offspring.
I did know that mantises acting in sexual cannibalism was something that happened. I did not know the many benefits that it brings the female. It really is all about survival and making sure that your genes get passed down to the next generation, and mantises are obviously willing to do anything to ensure that it happens
It was interesting to learn more about how cannibalism aided the female in her reproductive efforts. Even though I was aware that this was a common occurrence in the cycle of a male mantis’ life (the getting eaten part) but I never understood the drive behind eating her partner. I also really love the title!
-written by Anna
I have heard before that the female praying mantis engages in sexual cannibalism, but I never knew the reason why. I think that it is very interesting that the female eats her partner as a form of sustenance and nutrition in order to lay more eggs. I also thought it was interesting that males are actually able to mate more than once and that they actually strategically pick their mates in order to avoid getting eaten.
Wow what an interesting article! The idea of sexual cannibalism is super fascinating, and I wonder how this behavior originated in the Chinese Mantis. I sure am glad that I am not a male Chinese Mantis right now!
It’s interesting to note that male populations outnumber female populations before the mating season, but dwindle to 70% of the original population due to female cannibalism.
I think I’ve seen one of these in my yard before, but I didn’t think anything of its brownish color. I knew some spiders engage in sexual cannibalism but it was interesting to learn that the Chinese Mantis does too.