Wasps and other insects use a decentralized respiratory system, unlike mammals that rely on lungs and a circulatory system to move oxygen. This fundamental difference in physiology allows them to effectively “hold their breath” for a surprising duration. The precise time varies widely depending on environmental conditions, but the underlying biology explains why a wasp can sometimes revive after being submerged for minutes.
The Tracheal System and Insect Respiration
A wasp does not possess lungs, and its blood, called hemolymph, does not transport oxygen. Instead, the insect’s respiratory system is the tracheal system, a network of air-filled tubes independent of its circulatory system. This system branches into smaller units, called tracheoles, which directly deliver oxygen to nearly every cell in the body.
Air enters this network through tiny external openings called spiracles, located along the sides of the wasp’s thorax and abdomen. Each spiracle acts as a muscular valve that the wasp can open and close, regulating the intake of oxygen and the release of carbon dioxide. The primary function of closing these spiracles is to conserve water vapor and prevent desiccation. This mechanism also allows the wasp to seal its internal oxygen supply, enabling survival when submerged or in an oxygen-deprived environment.
How Wasps Survive Underwater or Anoxia
When a wasp is submerged in water, it closes its spiracles to prevent the tracheal system from flooding. For an active, stressed wasp, survival until motionlessness typically lasts only a few minutes (two to five minutes). The wasp is not necessarily dead, but incapacitated from acute oxygen deprivation. Internal air reserves deplete quickly, forcing a switch to anaerobic metabolism, which does not require oxygen.
This physiological switch allows the wasp to survive low-oxygen conditions, known as anoxia, for much longer periods. The actual duration of survival can range from half an hour to several hours, depending on the specific conditions. Once removed from the water and exposed to air, the wasp can often revive and fly away, explaining why seemingly drowned wasps “come back to life.” The limiting factor during this time is the accumulation of metabolic byproducts, not the lack of air itself.
Variables That Determine Survival Duration
The broad range of survival times, from minutes to hours, results from several variables influencing the wasp’s metabolic rate. Primary is temperature, as wasps are cold-blooded insects. Colder water or air drastically lowers the wasp’s metabolism, reducing its need for oxygen and slowing the production of toxic byproducts. A cold, resting wasp will survive anoxic conditions substantially longer than a warm, active one.
The wasp’s activity level is also a major determinant, as an active or stressed insect rapidly depletes its internal oxygen reserves and consumes energy much faster. An insect struggling to escape water will succumb to anoxia much quicker than one that is chilled and resting. Another element is the species of wasp, with different types exhibiting varying metabolic needs and spiracle efficiencies.
The ultimate limiting factor is the buildup of waste products from anaerobic metabolism, primarily lactic acid, which lowers the internal pH of the hemolymph. High concentrations of carbon dioxide that cannot be expelled also contribute to physiological stress. This combination of depleted energy stores and metabolic acidosis eventually leads to cellular damage and death if the anoxic period is extended too long.