A ten-year presence that only recently exploded

Two large praying mantis species native to Asia have been quietly establishing themselves across parts of Europe for roughly a decade. What's changed recently isn't their presence, but their numbers, and the scientific recognition of what that growth actually means. A study published in the open-access Journal of Orthoptera Research and led by Roberto Battiston of the "G. Zannato" Museum of Archaeology and Natural Sciences has now formally classified Hierodula patellifera and Hierodula tenuidentata as Invasive Alien Species, a designation that carries real regulatory and conservation weight rather than being merely descriptive.

That's a meaningful shift in framing. Mantises have historically occupied a favorable place in how people think about insects — genuinely admired across cultures, sometimes viewed as mystical guides, and valued by ecologists specifically because native mantis populations tend to serve as reliable indicators of a healthy, biodiverse ecosystem. Battiston's research flips that association for these two species specifically: instead of signaling ecosystem health, their expanding presence now signals its disruption.

A breeding advantage that dwarfs the native competition

The core of what makes these two Asian mantis species such an effective invader comes down to sheer reproductive output. According to the study, Hierodula tenuidentata produces an average of roughly 209 nymphs per ootheca — the brownish, spongy egg case each female lays — compared to Europe's native Mantis religiosa, which produces meaningfully fewer offspring per egg case. That's nearly double the reproductive output of the species these invaders are displacing, a gap large enough on its own to drive rapid population growth even before factoring in any other competitive advantage.

The invasive species compound that reproductive edge with another trait: their young are considerably less prone to cannibalizing each other than native mantis nymphs are, according to coverage of the study by ScienceDaily. Mantis nymphs eating siblings shortly after hatching is a well-documented population check in many native species. With that natural population brake largely absent in the invasive Asian species, a much larger share of each oversized brood survives to adulthood than would be expected from comparable native mantis reproduction.

Turning a native mating ritual into a tool for population suppression

The most striking mechanism Battiston's team documented involves how these invasive species interact directly with native mantis populations, and it's grimmer than simple competition for food or territory. Cannibalism during mating is standard behavior across many mantis species broadly — female mantises consuming their partners after or during copulation is a well-known evolutionary quirk, not something unique to this invasion. What Battiston's research describes is a distorted, cross-species version of that same dynamic: large invasive females release pheromones that attract native male European mantises, according to reporting from EuropeSays. When those native males attempt to mate with the invasive females, they're frequently caught and eaten instead.

That's a mechanism operating directly against the reproductive capacity of the native species, not merely alongside it. Every native male mantis lured in and consumed by an invasive female is a male that will never contribute to the next generation of Europe's own mantis population — meaning the invasive species isn't just out-competing native mantises for food and habitat, it's actively removing individuals from the native breeding population through a mechanism the native species' own mating instincts make it vulnerable to.

The predation extends well beyond other mantises

Reproductive interference with native mantises is only part of what makes Hierodula patellifera and Hierodula tenuidentata concerning from a conservation standpoint. Both species are aggressive, broad-spectrum predators, and researchers have documented them preying on important native pollinators, including honeybees, alongside small protected vertebrates such as lizards and tree frogs. One striking piece of video evidence cited in coverage of the study shows Hierodula patellifera simultaneously eating both a wasp and a bee — a small but visceral illustration of just how indiscriminately these mantises are willing to hunt.

That predation pattern matters beyond the individual prey species involved. Pollinators are already under pressure from multiple directions across Europe and globally — habitat loss, pesticide exposure, and climate stress among them. Introducing a large, efficient new predator specifically targeting pollinating insects adds a further pressure to populations that, in many cases, were already showing signs of strain well before these mantis species began expanding their range.

Climate change is opening the door northward

The invasion's geographic spread isn't happening randomly — it's tracking a specific climate pattern. Battiston's research links the mantises' northward expansion directly to warming conditions, both from broader climate change and from the localized warmth generated by urban environments, since cities tend to run measurably warmer than surrounding rural areas. Mantises are cold-blooded, meaning their survival and reproductive success are directly constrained by ambient temperature, particularly overnight lows during their breeding season.

That temperature sensitivity is exactly why this summer's weather patterns matter for the invasion's trajectory. Spain, Portugal, France, and southern Britain experienced a significant heat surge in early July 2026, with overnight lows in Madrid running nearly 9 degrees Celsius above the seasonal average, according to ScienceBlog's coverage of the study. Warmer nights specifically, rather than simply hotter daytime peaks, appear to be a critical factor enabling these mantises to survive and breed successfully in regions that would previously have been too cold for them, opening territory further north each year that warming trends continue.

What citizen scientists can actually do about it

Battiston's team isn't treating this purely as an academic finding — the research explicitly frames citizen involvement as a practical containment tool. The invasive species' egg cases are well-exposed and easily recognizable on branches during certain seasons, and removing them is straightforward and doesn't harm anything once identified correctly. Battiston cautions, however, that the public should always consult a specialist before removing any mantis egg case, specifically to avoid accidentally destroying the eggs of native mantis species rather than the invasive ones — an important distinction given how visually similar the egg cases of different mantis species can appear to an untrained eye.

That caution reflects a broader tension running through this entire story: distinguishing between a native species worth protecting and an invasive one worth removing requires expertise that most casual observers simply don't have, even when they're motivated to help. Battiston's framing of the invasion as "a powerful reminder of how human activity shifts natural boundaries" points toward a conservation challenge that's become increasingly common across Europe and elsewhere — species expanding their range not through any single dramatic event, but through the slow, compounding effects of a warming climate steadily removing the barriers that once kept them contained.

*This article was researched using publicly available reporting from ScienceDaily, EurekAlert, Phys.org, SciTechDaily, ScienceBlog, EuropeSays, and the peer-reviewed study published in the Journal of Orthoptera Research by Roberto Battiston and colleagues at the "G. Zannato" Museum of Archaeology and Natural Sciences. It is intended for informational purposes.*