Earwigs are common, nocturnal insects found globally, easily recognized by the forceps-like pincers extending from their abdomen. Their frequent presence in damp, dark places naturally leads to the question of whether they can survive being completely underwater. An earwig cannot breathe underwater like a fish, but its unique biology allows it to survive submersion for a surprisingly long time.
The Earwig Respiratory System
Earwigs, like nearly all terrestrial insects, rely on the tracheal system for gas exchange, which is completely separate from their circulatory system. This dense network of internal tubes carries oxygen directly to the tissues and cells. The insect’s blood, or hemolymph, does not play a role in transporting oxygen throughout the body.
The tracheal system connects to the outside world through small, paired openings along the sides of the earwig’s body called spiracles. These openings function as valves, allowing air to enter the body and carbon dioxide to exit. The entire process depends on a direct supply of atmospheric air, as this respiratory design is not equipped to extract the minute amounts of dissolved oxygen found in water.
The earwig’s breathing mechanism contrasts sharply with the gills of aquatic animals, which are designed to separate oxygen molecules from water molecules. Since the earwig’s internal tubes are air-filled, flooding the system with water prevents gas exchange from occurring. This fundamental difference means that true aquatic respiration is physiologically impossible for this insect.
Submersion Survival Strategies
When an earwig is suddenly submerged in water, its immediate reaction is a survival mechanism to seal off its respiratory openings. The spiracles are equipped with closer muscles, allowing the earwig to actively shut these valves to prevent water from entering the tracheal tubes. This action effectively means the earwig is holding its breath, relying on the limited air already contained within its tracheal system and oxygen diffused into its body tissues.
This ability to seal its spiracles is primarily an adaptation to prevent water loss, or desiccation, in dry air, but it serves a dual purpose underwater. The insect can survive a significant period of full submersion until it depletes its stored oxygen or carbon dioxide buildup becomes toxic. Observational evidence suggests that earwigs can survive full submersion for a few hours, though this is near their limit.
Their overall tolerance for water contact is remarkable, as adults have been observed floating on the surface for up to 24 hours. During this time, the earwig is not breathing water but is effectively trapped on the surface, minimizing oxygen consumption while waiting for a chance to reach dry land. This combination of a sealed respiratory system and an extremely low metabolic rate allows them to endure accidental contact with water for extended periods.
Earwig Habitat and Water Tolerance
The question of underwater breathing arises due to the earwig’s strong preference for wet, humid environments. Earwigs are nocturnal and spend their days hiding in places where moisture is consistently high, such as under mulch, stones, logs, or leaf litter. They seek out these damp locations to prevent desiccation, a condition that can be lethal to insects.
This need for moisture often leads them into areas like basements, bathrooms, or potted plants in homes, which are mistakenly assumed to be their natural aquatic habitat. Their behavior is driven by the need for high humidity, not standing water. A humid microclimate slows the evaporation of water from their bodies, which is necessary for survival.
The confusion lies in the difference between needing a moist environment and being truly adapted to an aquatic one. An earwig requires high humidity to live comfortably, but it is still a terrestrial insect that must breathe atmospheric air. They tolerate water contact far better than many other land-dwelling insects due to their spiracle-sealing ability, which is a key part of their survival strategy.