The insect order Dermaptera, commonly known as earwigs, comprises over 2,000 species recognized by the distinct, forceps-like pincers at the end of their abdomens. These insects are often discovered in groups under rocks, logs, or mulch, which can lead to the assumption they live in structured colonies similar to ants or bees. Earwigs do not form the intricate, permanent, and multi-generational colonies seen in truly social insects.
Social Structure
The societies of ants, bees, and termites are defined by a high level of organization known as eusociality, which requires three specific characteristics. These include an overlap of generations living within the same nest, a cooperative system for raising the young, and a reproductive division of labor, often involving sterile worker castes. Earwigs entirely lack this complex social arrangement and the specialized castes that define a true colony.
The social life of earwigs is best described as subsociality, meaning they exhibit parental care but do not meet the criteria for eusocial living. They are primarily solitary outside of the breeding season, with individuals fending for themselves. Earwigs do not establish a queen or maintain a permanent, centralized nest where sterile individuals contribute to the collective good.
Parental Care
The most advanced social behavior earwigs display is the remarkable maternal care provided by the female. After mating, the female prepares a small, secluded nest, often in a burrow or under debris, where she deposits a clutch of eggs. She remains with her eggs throughout the incubation period, which can last for several months over winter in some species.
This protective phase involves active care, such as guarding the eggs against predators and regularly cleaning them to prevent the growth of mold or fungus. Without this constant attention, the egg clutch is highly vulnerable to infection and predation. Once the nymphs hatch, the mother continues to protect them within the nest for a short period, typically through their first or second molt.
During this early stage, the mother may even forage and bring food back to her offspring, which is a rare behavior among non-eusocial insects. This family unit is temporary, lasting only a few weeks until the young are mobile enough to disperse and begin a solitary existence. This maternal investment highlights the subsocial nature of the species.
Aggregation Behavior
The visual evidence of large groups of earwigs, which often suggests colonial life, is actually a result of simple aggregation behavior. Earwigs are nocturnal insects that require dark, narrow, and moist microhabitats during the day to avoid desiccation. This environmental necessity leads multiple individuals to seek refuge in the same optimal spot, such as under a damp piece of wood or a flowerpot.
This tendency to seek close physical contact with surfaces and other earwigs is known as thigmotaxis, and it drives the formation of clusters. The group is essentially a collection of independent individuals sharing a favorable resting place, not a cooperative workforce. Individuals can alternate between solitary life and group living, demonstrating that the aggregation is facultative and not obligatory for survival.
The density of the population within a suitable area means many earwigs cluster together, giving the false impression of a coordinated colony. This behavior is driven by shared ecological needs for shelter and moisture rather than a true social structure involving division of labor. The only sustained social unit is the mother and her immediate young before they disperse.
Addressing Common Concerns
The most widespread concern about earwigs is rooted in the ancient myth that they intentionally crawl into human ears, a belief that is entirely unfounded. Despite the name, earwigs do not seek out human ears as a place to live or lay eggs. They prefer damp, dark crevices in the environment, and the name likely stems from old folklore.
Earwigs are generally considered nuisance pests because of their tendency to gather in homes and gardens when seeking shelter. They are omnivores, feeding on a varied diet that includes decaying organic matter, moss, lichens, and sometimes plant seedlings. While they can damage flowers or garden produce, they can also be beneficial predators, consuming small garden pests like aphids and mites.
Their presence indoors is usually accidental, occurring when outside conditions become too dry or too wet, causing them to move into damp areas like basements or bathrooms. Earwigs are largely harmless to humans. While their pincers look intimidating, they are used for defense or in territorial disputes with other earwigs and pose no threat.