Praying mantises absolutely eat each other, and they do so across multiple life stages and contexts. The most famous example is sexual cannibalism, where a female devours her mate during or after copulation. In wild populations of the European mantis, this happens in roughly a third of observed matings. But mantises also eat each other as newly hatched siblings, as rival adults competing for territory, and sometimes before mating even begins. Cannibalism is woven deeply into mantis biology, driven by hunger, reproductive strategy, and the simple fact that mantises are indiscriminate ambush predators that treat almost anything the right size as a meal.
How Often Does Sexual Cannibalism Actually Happen
For decades, the popular image of praying mantis sex has been that the female always bites the male’s head off. That idea was partly an artifact of early lab experiments, where stressed, starving mantises in small enclosures behaved more aggressively than they would in the wild. A field study of the European praying mantis (Mantis religiosa) found that sexual cannibalism occurred in 31% of matings observed in nature. That is a real and meaningful rate, but it also means the majority of males survive the encounter.1Animal Behaviour. Sexual cannibalism in the praying mantid, Mantis religiosa: a field study The study also noted that mating behavior in the wild looked similar to captive observations in one key respect: males were always cautious in their approach and performed no courtship display before mounting, suggesting they treat every mating attempt as a potentially lethal encounter.
Rates vary dramatically by species, too. Some mantis species are far more cannibalistic than others. The springbok mantis (Miomantis caffra) is considered highly cannibalistic, while the New Zealand native mantis (Orthodera novaezealandiae) is much less so.2Behavioral Ecology and Sociobiology. Behavioural correlations and aggression in praying mantids With over 2,400 mantis species worldwide, sexual cannibalism is not a universal constant. It ranges from rare to nearly routine depending on the species, the female’s condition, and how often males and females encounter each other in the environment.
Why Females Eat Their Mates
The simplest explanation is hunger. A male mantis is a large, protein-rich meal that walks directly toward a female. Research on the false garden mantis (Pseudomantis albofimbriata) found that females who cannibalized their mates substantially improved their body condition and went on to produce heavier egg cases than females who did not cannibalize. The study also showed that females in poor physical condition were more likely to eat their mates than well-fed females, supporting the idea that sexual cannibalism functions as a foraging strategy.3Oxford Academic (Behavioral Ecology). Female praying mantids use sexual cannibalism as a foraging strategy to increase fecundity
This dynamic becomes even more pronounced when food is scarce. When males that had experienced low mate-encounter rates (making them more desperate to mate) were paired with hungry females, rates of sexual cannibalism jumped significantly. Males that had rarely encountered females took greater risks during approach and courtship, and hungry females capitalized on that boldness.4PubMed Central. Low mate encounter rate increases male risk taking in a sexually cannibalistic praying mantis The pattern is straightforward: a hungry female is more dangerous, and a mate-deprived male is more willing to gamble with his life.
Does Getting Eaten Actually Help the Male’s Genes
This is where the story gets genuinely strange. One of the central questions in evolutionary biology around mantis cannibalism has been whether males derive any reproductive benefit from being consumed. A study on the Chinese mantis (Tenodera sinensis) used radiolabelled food to trace where the male’s body nutrients ended up after cannibalism. The results were striking: females who cannibalized their mates incorporated significantly more male-derived amino acids into their eggs and reproductive tissues compared to females who mated without cannibalizing. Cannibalistic females also produced more eggs afterward.5PubMed Central. Sexual cannibalism increases male material investment in offspring: quantifying terminal reproductive effort in a praying mantis
In other words, a cannibalized male’s body literally becomes part of his own offspring. His amino acids get shunted directly into the eggs he fertilized. This does not mean males “want” to be eaten. But from a cold evolutionary accounting standpoint, a male who mates successfully and then gets consumed is investing his entire body into the next generation. This is sometimes called terminal reproductive effort: if a male’s chances of mating again are low anyway, his remaining body mass serves his genes better as food for his mate than as fuel for his own survival.
That said, researchers have found clear evidence that the situation is better described as sexual conflict than mutual cooperation. Males of the same species behaved in ways that were clearly oriented toward avoiding being eaten, such as cautious approaches and attempts to flee after mating.6PubMed. Complicity or conflict over sexual cannibalism? Male risk taking in the praying mantis Tenodera aridifolia sinensis Males are not passively offering themselves up. They are trying to mate and escape. When that fails, the silver lining is that their body nutrients end up in their own offspring, but it is a consolation prize, not a chosen strategy.
How Males Try to Survive the Encounter
Male mantises have evolved a suite of behaviors that make mating less likely to end in death. A study of the Australian mantis (Pseudomantis albofimbriata) catalogued several tactics. Most males tried to avoid being detected at all, approaching from behind or from angles outside the female’s visual field. Others moved in an extremely slow, stealthy manner, creeping toward the female over long periods. Some males mounted females opportunistically from the rear without any preceding approach that might draw attention. No courtship display was observed in this species, which makes sense: drawing attention to yourself when your partner might eat you is a bad survival strategy.7Journal of Ethology. Male mating behaviour reduces the risk of sexual cannibalism in an Australian praying mantid
The stealth approach is not foolproof, and in some species, the initial encounter between male and female is anything but subtle. In the springbok mantis, researchers found that most first contacts between the sexes involve a violent struggle in which each individual tries to be the first to grab the other with their raptorial forelegs. The one who grabs first gains a decisive advantage: if the female grabs first, she eats; if the male grabs first, he can attempt to mount and mate.8PubMed Central. Male coercion and female injury in a sexually cannibalistic mantis This wrestling match is a reminder that mantis mating, in highly cannibalistic species, is not a passive affair where the female simply strikes. It can be an active physical contest between two armed predators.
The Femme Fatale Trap
One of the more unsettling discoveries in mantis research involves chemical deception. Female mantises attract males using airborne chemical signals, or pheromones. In a straightforward system, these pheromones would honestly advertise the female’s quality: her size, health, and egg-producing capacity. Males would then prefer to approach the most fecund, highest-quality females. And in well-fed populations, this is roughly what happens.
But in the false garden mantis, researchers discovered that very poorly nourished females attracted significantly more males than any other group, despite being in worse condition and producing fewer eggs. When the hungriest females were removed from the analysis, there was a positive correlation between fecundity and attractiveness, suggesting the signaling system is normally honest. The starving females appeared to be exploiting this system, pumping out attractive pheromones to lure males not primarily as mates but as meals. This was the first empirical evidence of what researchers call the Femme Fatale hypothesis: the idea that some females use sexual signals dishonestly to exploit males as prey.9PubMed Central. Sexual deception in a cannibalistic mating system? Testing the Femme Fatale hypothesis
A study on the springbok mantis found the same pattern in even starker terms. Males in a choice experiment selected the pheromonal signals of low-condition females twice as often as those of high-condition females. Those low-condition females then attacked males three times more frequently and cannibalized them four times more often than well-fed females.10Functional Ecology. Luring cannibal: Dishonest sexual signalling in the springbok mantis The males were being chemically baited toward the most dangerous possible partner. From the female’s perspective, the payoff is clear: cannibalizing a male when you are starving provides a massive nutritional boost and can rescue your reproductive output. From the male’s perspective, it is a trap with no reliable way to distinguish a genuinely high-quality mate from a hungry predator wearing the same perfume.
Siblings Eating Siblings
Sexual cannibalism gets most of the attention, but mantises start eating each other long before they reach adulthood. A praying mantis egg case, called an ootheca, can contain dozens to hundreds of eggs. When they hatch, all those tiny nymphs emerge into the same small area at roughly the same time. They are hungry, they are surrounded by other small moving things, and they are already equipped with the same predatory instincts they will use as adults.
Research on the springbok mantis found that newly hatched nymphs did not disperse quickly after emerging from the ootheca, meaning full siblings remained clustered together for days. Despite this extended proximity, the nymphs showed no ability to recognize or avoid eating their siblings. Cannibalism rates were equally high among groups of full siblings and groups of mixed parentage.11Journal of Ethology. Cannibalistic siblicide in praying mantis nymphs (Miomantis caffra) The researchers concluded that for a generalist ambush predator like a mantis, the benefits of being indiscriminately aggressive toward anything that moves outweigh whatever evolutionary advantage might come from sparing relatives. A nymph that hesitates to strike at a sibling-sized object is a nymph that might also hesitate to strike at prey, and in the competitive environment around a freshly hatched ootheca, hesitation is costly.
This sibling cannibalism serves as a kind of natural thinning mechanism. The nymphs that are slightly larger, faster, or better positioned get a head start by consuming their brothers and sisters. For the survivors, it provides an early meal that may be the difference between making it through the first few vulnerable days of life and starving. It is brutal, but it is also the logical extension of being a predator from birth.
Does Aggressiveness Toward Prey Predict Cannibalism
You might assume that the most aggressive mantis species are also the most cannibalistic, and at a species level, this pattern holds up. When researchers compared the highly cannibalistic springbok mantis with the less cannibalistic New Zealand native mantis, the more cannibalistic species was also more aggressive toward prey in general. But here is where it gets interesting: within a single species, an individual mantis’s aggressiveness toward prey did not predict whether that particular individual would cannibalize a mate.12Behavioral Ecology and Sociobiology. Behavioural correlations and aggression in praying mantids
This finding suggests that sexual cannibalism is not simply a side effect of being a generally aggressive hunter. A female who attacks crickets with enthusiasm is not necessarily more likely to eat her mate than a more laid-back hunter of the same species. The decision to cannibalize a mate appears to be driven more by the female’s nutritional state and the specific circumstances of the encounter than by some fixed personality trait of being “extra aggressive.” Species-level differences exist, likely shaped by evolutionary pressures particular to each species’ ecology, but within a species, the hungriest female is the most dangerous regardless of her baseline temperament.
What Happens When You Keep Multiple Mantises Together
This is one of the most common practical questions people have about mantises, especially those who keep them as pets or breed them in captivity. The short answer is that housing two or more mantises in the same enclosure almost always ends with one of them eating the other. It does not matter whether they are male and female, two females, or two males. Mantises are solitary predators with no social tolerance for conspecifics. They do not form colonies or pairs. Every other mantis in their environment is either a meal or a threat, and often both.
The exceptions are limited. Some communal species, particularly in the genus Phyllocrania (ghost mantises) and a few others, tolerate being housed together more readily, especially when well-fed and given sufficient space. But even in these species, cannibalism still occurs if one individual is noticeably smaller or if food becomes scarce. For the vast majority of the roughly 2,400 known species, cohabitation is a death sentence for one of the occupants.
Captive conditions can actually inflate cannibalism rates compared to the wild. In nature, mantises have space to avoid each other. Males can approach from a distance, choose their angle, and retreat. In a terrarium, there is no retreat. This is part of why early laboratory studies gave the impression that sexual cannibalism was nearly universal: the confined conditions eliminated the escape options that wild males rely on. Modern researchers are careful to account for this when designing experiments, but hobbyists housing mantises together face the same inflated risk.
Can a Male Mantis Finish Mating Without His Head
This is one of the most frequently asked follow-up questions, and the answer is yes. A male mantis can continue copulating after being decapitated because the movements involved in mating are controlled by nerve ganglia in the abdomen, not by the brain. In fact, early researchers noted that decapitation sometimes appeared to remove inhibitions, making the male’s abdominal thrusting more vigorous. The male’s nervous system is decentralized enough that losing the head does not immediately stop reproductive function.
In the wild, this means that when a female begins eating her mate head-first during copulation, she does not necessarily cut the mating short. The male’s body can continue transferring sperm while the female consumes the head and thorax. From the female’s perspective, this is doubly efficient: she gets both the sperm and the meal. From an evolutionary standpoint, the male’s genes still get passed on even in this grim scenario, which may be one reason natural selection has not eliminated the possibility of headless mating. If decapitation during sex were always fatal to reproduction, males whose nervous systems shut down immediately upon losing the head would have left fewer offspring than males whose bodies kept going.
Cannibalism Outside the Mating Context
While sexual cannibalism and sibling cannibalism get the most research attention, mantises also eat each other in contexts that have nothing to do with reproduction. Any encounter between two mantises of different sizes can end in one consuming the other, period. A large female will eat a smaller female. A nymph in a later developmental stage will eat younger nymphs. Even adult males will eat smaller males if the size difference is sufficient.
Size is the primary factor. Mantises are visual predators that respond to movement and relative size rather than to species identity. A mantis does not evaluate whether the creature in front of it is a potential mate, a rival, or a different species entirely. If it moves and it is small enough to catch, the mantis strikes. This is the same indiscriminate predatory behavior documented in the nymph sibling cannibalism studies: mantises do not discriminate between kin and non-kin, between conspecifics and prey species, or between potential mates and food items. They discriminate between things they can overpower and things they cannot.
This indiscriminate aggression is part of what makes mantises such effective generalist predators. They eat insects, spiders, and occasionally small vertebrates like lizards and hummingbirds, and they apply the same ambush-and-strike calculus to all of them. A fellow mantis just happens to be another item on the menu. The distinction we draw between “cannibalism” and “predation” is meaningful to us but meaningless to the mantis. It is all just hunting.