Mantis

• 1. Introduction

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  Mantises can swivel their heads nearly 180 degrees, turning a hunter's gaze almost fully behind it without moving the rest of the body. The order Mantodea contains more than 2,400 species, scattered across temperate and tropical habitats around the world. Their common name, praying mantis, comes from the upright stance they hold while waiting, forearms folded as if in prayer. That calm pose is deceptive. The folded arms are spiked traps, ready to snap shut. This documentary asks how a small ambush hunter finds and seizes its prey, and how it hides from the animals that hunt it. It asks why a female sometimes eats her mate, and what the scientists watching her have argued about. It also asks why early civilizations treated this insect with awe, and why people still keep it, study it and copy it.

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• 2. Eyes and Forelegs

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  A single mantis eye can hold up to 10,000 ommatidia, the tiny lens units that build an insect's view of the world. Most of them watch for movement. When something stirs, the head whips round to bring the object onto the fovea, a small front patch of the eye with sharper focus. The mantis then tracks the target by turning its head to keep the image centered there. The eyes sit wide apart on the sides of the head, which gives a broad binocular field and precise stereo vision at close range. Unlike humans, mantises use that depth perception specifically to spot and capture prey.

  Four is the usual number of discoidal spines at the base of the femur on a mantis foreleg, though species range from none to five. The leg is built unlike the other four. The coxa and trochanter fuse into a segment about as long as the femur. Rows of tooth-like tubercles along the femur and tibia, plus a claw near the tip, complete the trap. Prey caught between them is held securely.

  Most mantises are generalist predators of arthropods that wait in ambush, camouflaged and still, or stalk with slow, stealthy steps. Once prey comes within reach, the strike is rapid. Larger mantises also eat smaller mantises of their own species, and sometimes small vertebrates such as lizards, frogs, fish and small birds.

  The ground mantises Entella, Ligaria and Ligariella break the waiting-game rule. They run across dry ground seeking prey, much as tiger beetles do. Another species, Euantissa pulchra, can tell prey types apart, approaching spiders that mimic non-aggressive ants far more often than spiders that mimic aggressive ones.

  In some species the foregut runs the whole length of the insect and can store prey for later digestion, which suits an animal that feeds intermittently. Pollen matters too: Chinese mantises that eat it live longer, grow faster and produce more young. What happens when the hunter becomes the hunted is the next problem.

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• 3. Disguise and Bluff

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  Frogs, lizards and birds eat mantises, and so do spiders, large hornets and ants. Hunting wasps of the genus Tachytes paralyze certain mantis species to feed their young. Against such a crowd of enemies, most mantises rely on camouflage. They are cryptically colored to resemble leaves or other backgrounds, which also helps them snare prey. Species living on bare earth or tree bark are flattened from back to belly, so they cast no revealing shadow.

  Flower mantises, which belong to different families, take disguise a step further. They resemble flowers convincingly enough to attract insects that arrive for pollen and nectar, making them aggressive mimics. In Africa and Australia, some species turn black after a molt near the end of the dry season. Bush fires break out then, and the dark coloring lets them blend into the burned landscape. Biologists call the effect fire melanism.

  A threatened mantis may rear up, spread its forelegs and fan its wings wide to look larger. Some species add bright colors and patterns on the hindwings and the inner surfaces of the front legs. A few also hiss by expelling air from abdominal spiracles. This is a deimatic display, a bluff, because mantises have no chemical protection. If the warning fails, the mantis may strike, pinch or bite, and a captured one can slash with its raptorial legs.

  Most mantises hunt by day, since their hunting relies on sight, but many species fly at night. Males of the family Liturgusidae are collected at night more often, which suggests they are more active in the dark or are drawn to light. Nocturnal flight helps males find less mobile females by detecting their pheromones, and it exposes them to fewer bird predators.

  The night has its own hunters, and mantises have an answer. They are the only members of their superorder with tympanate hearing, with two tympana in an auditory chamber in the metathorax. Most mantises hear only ultrasound. When a bat's echolocation calls quicken in frequency, signaling its approach, the mantis stops flying level and spirals toward the ground, sometimes after an aerial loop or spin.

  On the ground or on a stem, mantises show a rocking behavior, swaying rhythmically from side to side, as stick insects do. One proposed function is to look like vegetation moving in the wind. Another may matter more: the sway creates relative motion that lets the insect separate objects from the background. Ants, which prey on mantises, are avoided by genera such as Loxomantis, Orthodera and Statilia. Some early-instar mantises exploit that habit by mimicking ants themselves.

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• 4. Eggs and Winters

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  Between 10 and 400 eggs is the range a female may lay, depending on the species. In temperate climates, mating comes in autumn, while in the tropics it can happen at any time of year. After courtship, the male usually leaps onto the female's back and clasps her thorax and wing bases with his forelegs. He arches his abdomen to deposit sperm in a special chamber near the tip of hers.

  Glands in the female's abdomen produce a froth that hardens into a protective capsule. The capsule and the eggs inside together form the ootheca. Depending on the species, it may be fixed to a flat surface, wrapped around a plant or placed in the ground. Despite this durability, eggs are often eaten, especially by several species of parasitoid wasps.

  In a few species, mostly ground and bark mantises of the family Tarachodidae, the mother stands guard. The cryptic Tarachodes maurus sits on bark with her abdomen covering the egg capsule. She ambushes passing prey and hardly moves until the eggs hatch.

  Brunner's stick mantis from the southern United States has an even odder strategy. No male has ever been found, and the females breed parthenogenetically. The ability has also been recorded in at least two other species, Sphodromantis viridis and a Miomantis species, though those usually reproduce sexually.

  In temperate climates, adults do not survive the winter. The eggs enter a diapause and hatch in spring. Small species may hatch in 3-4 weeks, larger ones in 4-6 weeks. Mantises are hemimetabolous, passing through egg, nymph and adult with no pupal stage. The nymphs may be colored differently from the adults, and the early stages are often ant mimics.

  A nymph grows by molting its exoskeleton, from five to 10 times before adulthood, depending on the species. After the final molt, most species have wings, though some stay wingless or short-winged, particularly the females. Small species may live 4-8 weeks as adults, while large ones may live 4-6 months. Whether a male lives to see any of that depends on an encounter that scientists still argue over.

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• 5. The Cannibalism Question

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  About a quarter of male-female encounters in natural populations end with the male being eaten, according to observations in the wild. Around 90 percent of predatory mantis species show sexual cannibalism, and it is especially common in captivity. Adult males usually outnumber females at first, but the numbers may even out later, possibly because females selectively eat the smaller males.

  In Tenodera sinensis, 83 percent of males escape after an encounter with a female. But males mate more than once, so the chance of being eaten rises cumulatively with every pairing.

  The classic image is the female biting off the male's head, as she would with ordinary prey. Early researchers noticed that the male's movements could become even more vigorous afterward. Copulatory movement is controlled by a ganglion in the abdomen, not the head. They concluded that beheading might be a female strategy to improve fertilization while gaining a meal.

  Later work cast doubt on that story. The behavior appeared to be an artifact of intrusive laboratory observation. Mantises are highly visual and notice disturbances such as bright lights or moving scientists. Chinese mantises that were fed freely, and left undisturbed, showed elaborate courtship. The male performs a dance to shift the female's interest from feeding to mating. She may answer with a deimatic display, flashing the colored eyespots on the inside of her front legs. Whether cannibalism is fully natural in the field, or partly caused by human distraction, remains controversial.

  The reasons behind it are debated too. Experiments show that females on poor diets are likelier to eat their mates than well-fed ones. One hypothesis says submissive males gain an advantage, since males that are cannibalized copulate longer, in some cases doubling both the duration and the chance of fertilization.

  A different study pointed the other way. Males approached hungry females with more caution and stayed mounted on them longer. That suggests males that avoid being eaten may go on to mate with several females. Hungry females also attracted fewer males than well-fed ones.

  Dismounting after mating is the most dangerous moment, because that is when females most often attack. A longer ride on a hungry female may be a male waiting for an opportune moment to climb off. In Mantis religiosa, experiments found that the sex ratio of the surrounding group shapes male copulatory behavior, which in turn affects how likely the female is to cannibalize. The treatment with several competing males recorded the longest copulation and the lowest cannibalism, which supports a sperm competition hypothesis.

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• 6. A Name and a Lineage

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  The German entomologist Hermann Burmeister coined the name Mantodea in 1838. It joins two Ancient Greek words: mántis, meaning prophet, and eîdos, meaning form or type. The word mantid properly refers only to members of the family Mantidae, which was historically the only family in the order. In the United States, mantises was the usual plural, while mantids was common in the UK and elsewhere. Then the family was split in 2002. Today only about 75 of 430 known genera are mantids, so the rest, in 28 other families, no longer qualify.

  The tangled classification has a long history. Mantises and stick insects were once placed in the order Orthoptera alongside cockroaches and ice crawlers. Kristensen combined Mantodea with cockroaches and termites in 1991 as the order Dictyoptera, with Mantodea as a suborder. The closest living relatives of mantises are those termites and cockroaches.

  Beier proposed one of the earliest splits of the all-inclusive Mantidae in 1968, recognizing eight families. It took Ehrmann's reclassification into 15 families in 2002 before a multiple-family system was universally adopted. In 1997, Klass studied the external male genitalia and suggested that Chaeteessidae and Metallyticidae split from the other families early. Because the Mantidae and Thespidae had proved polyphyletic, the group was substantially revised by 2019 and now includes 29 families.

  Fossils are rare. By 2022, only 37 fossil species were known. Mantises are thought to have evolved from cockroach-like ancestors, and some of the earliest confidently identified fossils date to the Early Cretaceous. The Jurassic genus Lovec, reported in 2024 from the Upper Jurassic Karabastau Formation, pushed the record back.

  Cretaceous amber has preserved mantises too, including one from Japan with spines on its front legs like those of modern species. Most amber fossils are nymphs, while fossils in rock include adults. The Crato Formation in Brazil produced Santanmantis axelrodi, a mantis just 10 mm long, described in 2003. Its front legs were already adapted for catching prey. X-ray computed tomography can pull out details as small as 5 micrometers from well-preserved specimens.

  The raptorial forelegs also appear in unrelated insects. Mantisflies, in the order Neuroptera, are often confused with mantises, but the resemblance is convergent evolution. Mantisflies lack the leathery forewings called tegmina, and their antennae are shorter and less thread-like. Their grasping tibia is more muscular, and it bends back farther before shooting out to seize prey.

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• 7. Prophets and Femmes Fatales

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  The ancient Chinese dictionary Erya holds one of the earliest mantis references, in poetry where the insect stands for courage and fearlessness. A later text from 1108, the Jingshi Zhenglei Daguan Bencao, gives accurate details of the egg packages, the development cycle, the anatomy and the function of the antennae.

  Greek writers rarely mention the insect, but a fifth-century BC series of silver coins from Metapontum in Lucania, including didrachms, accurately shows a female mantis in threat posture. The 10th-century Byzantine encyclopedia Suda describes the insect called mantis as a pale green, clumsy, slow-moving locust and says some people watched its movements for augury. The Suda also records the phrase arouraia mantis, a proverb used to mock people who were sluggish and ineffectual yet treated as though they had insight.

  Other early cultures gave the mantis a more powerful role. For the Greeks, it could show lost travelers the way home. In the Ancient Egyptian Book of the Dead, the bird-fly is a minor god who leads the souls of the dead to the underworld. A list of 9th-century BC grasshoppers from Nineveh names the mantis necromancer, buru-enmeli, and soothsayer, buru-enmeli-ashaga.

  Local beliefs in Africa hold that the insect brings good luck. The Khoi and San of southern Africa revered it, and Afrikaans speakers among the first European settlers even called it Hottentotsgot, meaning god of the Hottentots. For the San, though, the mantis was only one form of the trickster-deity ǀKaggen, who could also appear as a snake, hare or vulture. Far across the Atlantic, mantises are a common motif in Luna Polychrome ceramics of pre-Columbian Nicaragua. They are believed to represent a deity or spirit called Madre Culebra, a powerful predator and symbol of female authority in oral traditions of western Nicaragua.

  Western descriptions of mantis biology grew more accurate in the 18th century. Roesel von Rosenhof illustrated mantises and their cannibalistic behavior in his Insekten-Belustigungen, or Insect Entertainments. In the early 1900s, people in the Ozarks region of the United States called them Devil's horses.

  Writers later used the insect for philosophy and drama. In Aldous Huxley's 1962 novel Island, two characters watch a pair of Gongylus gongylodes mating and reflect on the nature of death. Gerald Durrell's 1956 memoir My Family and Other Animals devotes four pages to a nearly even battle between a mantis named Cicely and a gecko named Geronimo. Durrell writes that the gecko "crashed into the mantis and made her reel, and grabbed the underside of her thorax in his jaws." Cicely answered by snapping both front legs shut on his hindlegs. The woodcut Dream by M. C. Escher shows a human-sized mantis standing on a sleeping bishop.

  Popular culture has settled on the female mantis as a femme fatale. Cartoonists including Cable, Guy and Rodd, LeLievre, T. McCracken and Mark Parisi have spread the idea. It ends Isabella Rossellini's short film on the life of a praying mantis, part of her 2008 Green Porno season for the Sundance Channel. The Deadly Mantis, a 1957 American science fiction monster film, pits mankind against a giant mantis.

  Two martial arts, developed separately in China, borrow the insect's movements and fighting strategies. One arose in the north and the other in the south, so both in English and in Chinese they are called Northern Praying Mantis and Southern Praying Mantis. Both are very popular in China and have been exported to the West in recent decades.

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• 8. Pets, Pests and Prototypes

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  In 2013, at least 31 mantis species were being kept and bred in the United Kingdom, the Netherlands and the United States. Mantises are among the insects most widely kept as pets. Because a mantis lives only about a year, people who want to keep them often breed them. Back in 1996, members of the Mantis Study Group were known to keep at least 50 species in captivity.

  Gardeners who avoid pesticides sometimes encourage mantises in the hope of controlling pests, and naturally occurring populations do provide some plant pest control. As biological control agents, however, mantises fall short. They do not specialize in a single pest, and they do not multiply rapidly when a prey species booms. Because they are general predators, their value in biological control is described as negligible.

  That verdict came after the hopes had already been acted on. Two species, the Chinese mantis and the European mantis, were deliberately introduced to North America as agricultural pest controls. They have since spread widely in both the United States and Canada.

  In 2016, the Association for the Advancement of Artificial Intelligence produced a prototype robot inspired by the praying mantis foreleg. Its multi-jointed front legs let the robot walk, climb steps and grasp objects, with a rotatable joint adding dexterity. Future models may carry a more spiked foreleg to improve grip and support more weight.

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