The European earwig (Forficula auricularia) is one of the most common insects on the planet and one of the most misunderstood. Found across Europe, much of Asia, and introduced to North America, Australia, and New Zealand, it is a nocturnal omnivore recognizable by the curved pincers (cerci) at the tip of its abdomen. Despite its somewhat menacing appearance, the European earwig is harmless to people and has no interest in human ears. What makes it genuinely remarkable is a combination of traits you would not expect from something most people encounter scuttling out from under a flowerpot: devoted maternal care, wings that fold in ways engineers are still trying to replicate, and a dual role in agriculture as both pest and beneficial predator.
Not One Species, but Several
For centuries, entomologists treated the European earwig as a single species with a wide range. That picture has changed. Genetic work analyzing mitochondrial and nuclear DNA across populations in the western part of the species’ range recovered five ancient lineages with distinct evolutionary histories, climatic preferences, and distribution patterns. Externally, these lineages look almost identical, which is why they went undetected for so long. The researchers concluded that what was called Forficula auricularia is actually a complex of at least four species, including three cryptic taxa that cannot be reliably told apart by eye and one, Forficula aeolica, that can be distinguished by physical features.1Zoological Journal of the Linnean Society. Speciation patterns in the Forficula auricularia species complex: cryptic and not so cryptic taxa across the western Palaearctic region
This matters beyond taxonomy. Recent work comparing two of these cryptic species, F. dentata and F. auricularia in the strict sense, found that nine reproductive traits differed between them, pointing to distinct breeding strategies.2PubMed. Alternative reproductive strategies in two cryptic species of the European earwig complex If you are reading about European earwigs in a pest management guide or a gardening column, the advice is probably still useful regardless of which cryptic species is in your yard. But for researchers studying earwig biology, the realization that field populations may contain a mix of lookalike species with different life histories changes how experiments need to be designed.
Pincers, Size, and Sexual Dimorphism
The most conspicuous feature of any earwig is its cerci, the pincer-like appendages at the rear of its body. In European earwigs, these differ markedly between the sexes. Males have longer, more curved forceps with greater variation in length and shape, while females have shorter, straighter ones that cluster around a narrow size range. This pattern, high variance and skew in males but a tidy bell curve in females, is a hallmark of a sexually selected trait. Male forceps serve as weapons in contests for access to females, and there is evidence that females also prefer males with longer forceps.3Animal Behaviour. Male–male competition and large size mating advantage in European earwigs, Forficula auricularia
An interesting wrinkle comes from studies on a related species, the maritime earwig: males whose left and right forceps were uneven in length actually won more fights against similarly sized opponents.4PubMed Central. Asymmetric forceps increase fighting success among males of similar size in the maritime earwig Asymmetry in a weapon sounds like it should be a disadvantage, but it may give one arm a leverage edge over the other during grappling. Whether the same holds in European earwigs specifically has not been confirmed, but the fighting mechanics are similar across the family.
Wings That Fold Like Origami
Most people never see a European earwig fly, and many assume they cannot. They can. Beneath the short, leathery forewings (called tegmina) lies a pair of hindwings that unfold to roughly ten times the area of the tegmina. Packing that much wing surface into such a small space requires an extraordinary folding pattern, one that has fascinated biomechanics researchers for years.
The hindwing folds along a radial fan pattern combined with a mid-wing crease, producing a compact package that snaps between two stable states: fully folded and fully deployed. During flight, only the base of the wing (the squama) is driven directly by muscles. The rest of the wing responds passively to the movement of the squama and air pressure, bending upward on the downstroke and downward on the upstroke. A set of fold lines and flexion lines act as built-in locks that prevent the wing from accidentally collapsing mid-flight. The wing beats at around 50 times per second.5Biology Open. Simultaneous optimisation of earwig hindwings for flight and folding
Engineers have taken notice. The folding geometry has been adapted into software that can generate artificial deployable structures of different sizes and configurations, with potential applications in architecture, aerospace, robotics, and everyday objects. The principle is the same: a large surface that stows compactly and locks reliably in both states. Researchers have pointed out that earwig lineages have been using this folding solution for at least 280 million years, which is a decent proof of concept.6PubMed Central. Earwig fan designing: Biomimetic and evolutionary biology applications More recent work has extended the idea into bistable origami structures with soft joints, aimed at applications in deployable structures and soft robotics.7PubMed. Earwig wing-inspired bistable origami: non-Euclidean units with soft joints
Devoted Mothers in the Insect World
Maternal care is rare among non-social insects, but European earwig females are genuinely attentive parents. After mating in autumn, a female excavates a small burrow in the soil, lays her eggs there, and tends them through the winter. She stays with the clutch, regularly grooming the eggs with her mouthparts and rearranging them. This is not just fussing. Experiments manipulating mold exposure showed that maternal egg attendance significantly improved hatching success, and the benefit was strongest when eggs were exposed to fungal spores. Females ramped up their grooming when mold was present, apparently both scraping spores off mechanically and transferring chemical substances, identified as hydrocarbons, onto the egg surfaces. Unattended eggs lost these protective chemicals quickly.8Behavioral Ecology. Maternal care provides antifungal protection to eggs in the European earwig
After hatching, the mother continues to provision and protect the nymphs for several weeks before they become independent. This level of care, sometimes called subsociality, places earwigs in a small club of insects whose offspring depend on parental investment for survival. It is one of the reasons the European earwig has become a model organism for studying the evolution of family life in insects.
This care system is not invulnerable. Heat stress experiments have shown that elevated temperatures disrupt several components of maternal behavior. Mothers exposed to heat were less likely to retrieve scattered eggs, and eggs that had been heat-stressed prompted altered grooming patterns depending on when the stress occurred.9Royal Society Open Science. Heat stress disrupts maternal care through independent effects on mothers and eggs Given that earwigs nest through winter and early spring, periods increasingly subject to temperature swings, this is a finding with real ecological implications.
Chemical Weapons and Defensive Secretions
The pincers get all the attention, but European earwigs also carry chemical defenses. Abdominal glands produce a foul-smelling secretion containing benzoquinones, specifically 2-methyl-1,4-benzoquinone and 2-ethyl-1,4-benzoquinone, which serve double duty as predator deterrents and antimicrobial agents that help sanitize the earwig’s immediate environment.10PubMed. Multifunctional weaponry: the chemical defenses of earwigs
Even earwig larvae produce chemical defenses, though they use different glands than adults do. Larval secretions contain the same core benzoquinones along with alkanes, and laboratory tests showed they were effective at discouraging foraging ants from feeding. Spiders, however, were not deterred, suggesting the chemical defense evolved primarily against invertebrate predators that hunt by touch and chemical sensing rather than by sight.11PubMed. The chemical defense in larvae of the earwig Forficula auricularia So from hatching through adulthood, European earwigs are never entirely undefended, even without their pincers.
Why They Cluster Together
If you have ever lifted a board or a piece of bark and found a writhing mass of earwigs, you have witnessed their strong aggregation behavior. This is not random. European earwigs actively seek out shelters already visited by other earwigs, and the attraction works across all life stages: adults are drawn to trails left by nymphs, nymphs to adult trails, and even first-instar nymphs still in the maternal burrow produce attractive cues that draw older nymphs. The pheromone responsible originates from secretions in the legs, specifically a tibial gland system.12Entomologia Experimentalis et Applicata. An Aggregation Pheromone in the European Earwig, Forficula auricularia
Further chemical analysis has implicated male cuticular lipids as another component. Bioassays of frass extracts, body-surface washes, and defensive exudates identified a complex mixture of alkanes, fatty acids, and the same defensive quinones described earlier, with the aggregation signal likely being a minor component of the male cuticular lipid blend.13PubMed. Pheromonal basis of aggregation in European earwig, Forficula auricularia L. (Dermaptera: Forficulidae) One curiosity: despite the strong aggregation behavior being partly chemical, a study testing whether gut microbiota composition predicted how gregarious individual females were found no link. The gut microbiome was highly variable between individuals, dominated by Proteobacteria and Firmicutes, but that variation did not map onto social tendency.14Behavioral Ecology. With or without you: gut microbiota does not predict aggregation behavior in European earwig females Whatever drives individual differences in how social a given earwig is, it does not seem to be the bacteria in its gut.
Omnivore, Pest, and Biological Control Agent
European earwigs are nocturnal omnivores that do most of their foraging during the first half of the night before returning to sheltered hiding spots. Dissections of their guts typically reveal both plant and animal material, commonly including moss, lichen, grass, and aphids.15Journal of Integrated Pest Management. Biology and Management of European Earwig in Orchards and Vineyards This omnivory is what makes them simultaneously useful and problematic in agriculture.
On the pest side, earwigs feed on soft fruits like strawberries, stone fruits, and grapes, chewing irregular holes that reduce marketability. They are also drawn to flower petals and seedlings in gardens, which is the main reason home gardeners tend to dislike them. On the beneficial side, they are voracious predators of aphids and other soft-bodied pests. Multi-year release trials in apple orchards showed that introducing 30 earwigs per tree did not produce a measurable effect in the first year, but by the second year, woolly apple aphid colonies were significantly shorter in trees that had received earwig releases compared to controls. The effect persisted into the third year.16PubMed Central. Earwig Releases Provide Accumulative Biological Control of the Woolly Apple Aphid over the Years The takeaway is that earwigs can genuinely suppress pest populations, but the effect is cumulative and takes time to build.
For home gardeners, the practical question is whether earwigs in your yard are doing more good than harm. In most cases they are, since aphid predation and organic-matter recycling outweigh the cosmetic damage to a few petals. If you grow soft fruit or prize dahlias, the calculus may shift. Simple physical traps, rolled-up damp newspaper or sections of garden hose set out overnight, exploit their thigmotactic instinct to seek tight, dark spaces and can reduce local populations without chemicals.
Surviving Winter
European earwigs spend winter underground as adults, a strategy that exposes them to cold stress and soil-dwelling parasites. Mortality is steep. Field studies found that between 60% and 90% of females do not survive the winter, with colder winters killing more of them. Males fare even worse and tend to die off early, often before the eggs they fathered have hatched. This aligns with the species’ life history: males contribute little after mating, while females need to survive long enough to tend eggs and rear nymphs in early spring.17Journal of Applied Entomology. Natural and human causes of earwig mortality during winter: temperature, parasitoids and soil tillage Soil tillage also matters. Mechanically disturbing the soil during the overwintering period exposes burrows to cold and predators, which is why earwig populations tend to be lower in tilled fields than in no-till systems or orchards with permanent ground cover.
How Human Activity Shapes Their Range
The European earwig is native to Europe and western Asia, but it has successfully invaded every other temperate continent. In Australia, where it is a well-established introduced pest, researchers found that climate alone did not fully explain where earwigs occurred. An index of human influence on the landscape was also important: there were regions with apparently suitable climate that earwigs had not colonized, likely because human activity there was too low to provide the disturbed habitats, transported materials, and irrigated landscapes that earwigs exploit.18PubMed. Climate, human influence and the distribution limits of the invasive European earwig, Forficula auricularia, in Australia In other words, we are not just accidentally spreading earwigs around the globe in shipping containers; we are also building the kinds of environments they thrive in once they arrive. Irrigated gardens, mulched beds, stacked timber, and compost bins are earwig paradise.
The Name and the Myth
No article about earwigs would be complete without addressing the name. “Earwig” likely derives from the Old English Ä“arwicga, roughly “ear insect,” and the persistent folk belief that earwigs crawl into sleeping people’s ears and bore into their brains. The brain-boring part is pure myth. But earwigs do occasionally enter human ears, just as many small insects do when they stumble into a warm, dark crevice while foraging at night.19PubMed Central. Earwig Crawling in the Ear: Myth or Truth There is nothing about ears in particular that attracts them. They are thigmotactic creatures, meaning they prefer to wedge themselves into tight spaces, and a human ear canal qualifies only by accident. The medical literature includes scattered case reports of earwigs found in ear canals, but these are curiosities, not a pattern that should keep anyone awake at night.
The myth has had remarkable staying power. Versions of it appear in European folklore dating back centuries, and the insect’s common name in many languages references ears: perce-oreille in French (“ear piercer”), Ohrwurm in German (“ear worm,” though this word now mostly refers to a catchy song stuck in your head). The association is so entrenched that even people who know it is false still feel a little uneasy picking one up.