Are Praying Mantises Native to Oregon?

Oregon is home to at least one native praying mantis species, but the large, conspicuous mantises that most Oregonians spot in gardens, on porches, and clinging to screen doors are almost certainly not native. The big green or brown mantises that draw attention every late summer and fall are overwhelmingly European mantises or Chinese mantises, both introduced to North America over a century ago. Oregon’s actual native mantis is a far smaller, ground-dwelling insect that most people never notice at all.

Oregon’s Actual Native Mantis

The minor ground mantis (Litaneutria minor) is the praying mantis species native to the western United States, and its range includes drier parts of Oregon east of the Cascades. Unlike the showy mantises people photograph and share on social media, this species is tiny, typically under an inch and a half long, with a mottled gray-brown coloring that blends into the dry grasses and rocky soils it lives among. It stays close to the ground rather than perching on tall plants, and its small size means it hunts tiny insects like gnats, aphids, and small flies rather than the large prey that bigger mantises tackle.

Because Litaneutria minor is so small, drab, and ground-hugging, most people who encounter a praying mantis in Oregon have found one of the introduced species instead. If the mantis you found is three or more inches long, bright green or tan, and sitting upright on a garden plant waiting to ambush something, it is almost certainly not native to Oregon.

The Two Introduced Species You Actually See

Two non-native mantis species have established self-sustaining populations across much of North America, including Oregon. The European mantis (Mantis religiosa) arrived in the northeastern United States in the 1890s, likely as a stowaway on nursery stock shipped from Europe. The Chinese mantis (Tenodera sinensis) was deliberately introduced around the same time, brought in as a potential pest-control agent for gardens and farms. Both species have spread widely since then, aided by people purchasing and releasing their egg cases.

The European mantis is the one Oregonians encounter most frequently. It reaches about two to three inches in length and is usually green, though brown and tan forms exist. The Chinese mantis is larger still, sometimes exceeding four inches, and tends toward a tan or light brown color with a green stripe along the edges of its wings. Both species are far bigger and more visible than the native ground mantis, which helps explain why many Oregonians assume praying mantises are a natural part of the landscape. They see them everywhere, so they feel like they belong.

A third non-native species, the narrow-winged mantis (Tenodera angustipennis), shows up occasionally in the Pacific Northwest as well, though it is less common than the other two.

How Non-Native Mantises Took Over the Landscape

The spread of introduced mantises across Oregon and the rest of North America was not purely accidental. Garden supply companies have sold Chinese mantis and European mantis egg cases for decades, marketing them as natural pest control. Gardeners buy them, release the nymphs into their yards, and the mantises establish local populations. Some of those populations persist year after year, spreading into surrounding habitat. The egg cases (called oothecae) are remarkably durable structures that survive freezing winters protected inside a foam-like casing, which allows both species to thrive even in Oregon’s colder eastern regions.

This deliberate introduction for pest control has created a situation where non-native mantises vastly outnumber native ones across most of the state. The practice continues today, with egg cases available at garden centers and through online retailers, often with no warning that the species being sold is not native.

What Introduced Mantises Actually Eat

The pitch for buying mantis egg cases usually frames them as garden guardians that devour pest insects. The reality is more complicated. Praying mantises are generalist ambush predators. They sit and wait for prey to come within striking distance, and they eat whatever they can catch, pest or not. A study that examined the diets of both the Chinese mantis and the European mantis using DNA analysis of their gut contents found that more than 75% of their diet consisted of herbivores, predators, and pollinators.¹ That means these mantises eat beneficial insects at least as readily as they eat pests. Butterflies, bees, hoverflies, spiders, and other predatory insects that gardeners want around are all fair game.

This indiscriminate diet is exactly what you would expect from a sit-and-wait predator. A mantis perched on a flowering plant is just as likely to snag a visiting pollinator as it is to catch an aphid-eating ladybug or a pest moth. The net effect on garden pest control is questionable at best, and the collateral damage to beneficial insect communities is real.

The Competition Problem for Native Species

When non-native mantises move into habitat where native species already live, the two groups end up competing for the same food and the same ambush sites. Research comparing the behavior of the introduced European mantis and the native bordered mantis (Stagmomantis limbata) found that the two species displayed no significant differences in their average behavioral tendencies, including risk-taking behavior, response to novel prey, and voracity.² In other words, the introduced species occupies essentially the same ecological role as the native one, hunting the same way with similar aggression. That overlap means direct competition for resources.

The bordered mantis, which is native to the southwestern United States and parts of the West Coast, is smaller than the Chinese mantis and roughly similar in size to the European mantis. When a larger non-native mantis competes with a smaller native one, the native species is at a disadvantage and can even become prey itself. Mantises are cannibalistic and will eat other mantis species without hesitation.

Mantises Eating Birds and Other Surprises

One of the more startling things about large mantises is that their diet extends well beyond insects. Both the Chinese mantis and the European mantis are big enough to capture hummingbirds, and documented cases of mantises catching hummingbirds at feeders have drawn widespread attention in recent years. Researchers have also documented mantises preying on songbird nestlings in several countries. Observations recorded female European mantises attacking and feeding on nestlings of different bird species, and similar predation events have been documented involving mantises and nestlings in Taiwan and Brazil.³

These are not freak events. Large female mantises in late summer are bulking up before laying their egg cases and will take the largest prey they can handle. Small lizards, frogs, and even mice have all been recorded as mantis prey. For Oregon gardeners who enjoy watching hummingbirds, placing mantis egg cases in your garden comes with a real, if small, risk that one of your mantises will station itself near your hummingbird feeder and wait for a meal.

How to Tell Which Mantis You Found

If you find a praying mantis in Oregon and want to know whether it is native or introduced, size is the quickest clue. If the insect is under an inch and a half, gray or brown, and you found it on the ground in dry grassland or sagebrush habitat east of the Cascades, you may have found the native ground mantis. If it is two inches or longer, green or tan, and perched upright on garden vegetation, it is almost certainly one of the introduced species.

Distinguishing between the European mantis and the Chinese mantis takes a slightly closer look. The European mantis has a distinctive black-ringed spot on the inside of each foreleg, visible when the legs are spread. It is typically two to three inches long. The Chinese mantis is larger, often exceeding three and a half inches, and its body tends to be narrower relative to its length with a tan or straw color and green wing margins. If you are in the Willamette Valley or along the coast, the European mantis is the species you are most likely to encounter. The Chinese mantis is present too but somewhat less common in western Oregon.

Should You Buy Mantis Egg Cases for Your Garden?

The practice of buying and releasing non-native mantis egg cases is so widespread that it feels harmless, but the ecological picture is worth considering before you do it. As noted earlier, introduced mantises eat pollinators and beneficial predatory insects at least as readily as they eat garden pests. If you are trying to manage aphids, caterpillars, or other specific pests, targeted approaches like encouraging native predatory insects, using row covers, or applying targeted biological controls tend to be far more effective than releasing a generalist predator that ignores most of the pests you care about.

Oregon’s native insect communities are already under pressure from habitat loss, pesticides, and climate shifts. Adding more non-native generalist predators to the mix does not help. Conservation entomologists have been raising this concern for years, pointing out that the widespread sale of non-native mantis egg cases essentially encourages people to release an invasive predator into their local ecosystem. The fact that mantises have been sold this way for decades does not make the ecological impact neutral.

If you genuinely want praying mantises in your garden for the sheer enjoyment of watching them, you will probably find them showing up on their own. Both introduced species are well established across Oregon and do not need help from purchased egg cases to maintain their populations.

Mantises as Biocontrol Against Invasive Pests

There is one area where the predatory appetite of large mantises has drawn genuine scientific interest. The spotted lanternfly, an invasive pest from Asia that has been devastating crops and trees across the eastern United States, is a potential target for mantis predation. Research testing five species of mantis against spotted lanternfly adults found that all of them readily preyed on the lanternfly, with feeding rates increasing as more lanternflies were available. The Chinese mantis, as the largest species tested, consumed more spotted lanternflies than the others, and adult Chinese mantises were more efficient predators than younger individuals.⁴

The spotted lanternfly has not yet established itself in Oregon, but it is on the state’s watch list. If it does arrive, the non-native mantises already present could play some role in controlling its spread, though relying on generalist predators to stop an invasive insect is rarely a complete solution. The irony of one non-native species potentially helping control another is not lost on ecologists, but the situation underscores how tangled these interactions become once multiple introduced species share a landscape.

Why Mantis Myths Persist

Several persistent myths about praying mantises circulate in Oregon and elsewhere. One is that killing a praying mantis is illegal. It is not, in Oregon or any other state. No praying mantis species in the United States has endangered or protected status that would make it illegal to kill one. This myth probably persists because people find mantises fascinating and assume something so charismatic must be legally protected.

Another common misconception is that praying mantises are rare. In reality, both introduced species are abundant in Oregon during late summer and fall, and their egg cases survive winter to hatch the following spring. The perception of rarity comes from the fact that mantises are ambush predators that sit motionless for long stretches, and their green or brown coloring makes them surprisingly hard to spot despite their size. You can walk past dozens in a garden without noticing any of them. When you do spot one, it feels like a special encounter, which reinforces the idea that they are uncommon.

A third myth is that the females always eat the males after mating. Cannibalism during or after mating does happen in mantises, but it is not universal. Studies across different species show that it occurs in a minority of mating encounters under natural conditions. The behavior is more common in captivity, where the female cannot leave and the male has fewer escape options. In the wild, males are cautious and often approach females slowly, sometimes waiting hours for the right moment. Many mating events end with both individuals walking away alive.

Attracting Native Mantises Instead

If you live in central or eastern Oregon, where the native ground mantis occurs, the best way to support it is to maintain or restore patches of native bunchgrass, sagebrush, and dry grassland. The ground mantis thrives in open, arid habitat with sparse vegetation, where it hunts small insects on or near the soil surface. Mowing, overgrazing, and converting native grassland to irrigated lawn or cropland all reduce habitat for this species.

Unlike the large introduced mantises, the ground mantis does not do well in lush garden settings. It is adapted to dry, exposed ground with scattered cover, and it is unlikely to colonize a well-watered vegetable garden in the Willamette Valley. Supporting this native species means supporting the broader dry-side ecosystem it belongs to, not releasing purchased insects into your backyard. For most western Oregon residents, encounters with truly native mantises will remain rare, and the mantises they see will continue to be the introduced European and Chinese species that have made themselves thoroughly at home.