Earwigs, with their distinctive pincer-like appendages, are a common sight in gardens and homes. The sight of multiple individuals gathered in a damp corner or under a piece of debris frequently leads to the question of whether they move together as a group. This perceived collective movement is usually the result of their basic habits and their need for specific microclimates. The reality is that their behavior alternates between a temporary family life and a strong attraction to the same environmental conditions.
The Truth About Earwig Social Behavior
Earwigs are not truly social insects like ants or honeybees, which exhibit cooperative brood care and overlapping generations. They are generally solitary creatures that spend their nights as individual, omnivorous foragers. Most of their active life involves moving alone to find decaying plant matter, small insects, or soft fruits.
When people observe many earwigs gathered together, they are witnessing aggregation, not coordinated group travel. This gathering is a temporary collection of independent individuals drawn to a single favorable location. Aggregation is a lower level of social organization than true sociality, lacking the division of labor or complex communication systems.
The European earwig uses a chemical signal called an aggregation pheromone, secreted by both males and females. This pheromone acts as a communal beacon, directing multiple solitary insects to the exact same resting spot. This chemical communication helps explain why dozens of earwigs can suddenly appear beneath a doormat or in cardboard.
Aggregation is primarily a survival strategy. By clumping together, they can better conserve moisture in dry conditions and potentially share warmth during cooler periods. The behavior is a practical response to external pressures rather than an internal drive to form a traveling pack.
The Phenomenon of Maternal Care
The most notable exception to the earwig’s solitary nature is the intense period of maternal care provided by the female. This subsocial behavior is rare among non-eusocial insects and is the only time earwigs form a cohesive family unit. The female typically excavates a small underground nest chamber where she lays a clutch of eggs, which can number between 20 and 80.
The mother remains with her eggs continuously, guarding them against predators and chasing away her mate. Her care involves meticulously cleaning the eggs to remove fungal spores. This maintenance is necessary, as studies show that only a small percentage of eggs hatch successfully without the mother’s constant grooming.
Once the eggs hatch into nymphs, the mother continues her protective role for a short period. She may bring food back to the nest and, in some species, regurgitate partially digested food for her offspring. This temporary family grouping lasts until the nymphs undergo their first or second molt, at which point they disperse to begin their solitary foraging lives.
Environmental Factors Driving Clustering
Clustering is driven by the earwigs’ need to find the right environment for rest. Earwigs are nocturnal, meaning they must seek secure, dark harborages to survive the day. Their bodies are prone to desiccation, so they require high levels of moisture in their resting places.
This need for a damp, shaded environment draws numerous individuals to the same spots, such as under stones, logs, leaf litter, or dense mulch. They also exhibit positive thigmotaxis, which is an attraction to tight, confined spaces where their bodies are in contact with surfaces. This behavior provides security and helps them regulate water loss.
The common sight of a mass of earwigs in a single location is simply a convergence of many solitary individuals seeking the same optimal conditions. Each insect is independently following its biological imperative for shelter, moisture, and darkness. Their collective appearance is a function of habitat preference, not a result of a coordinated migratory effort.