Insect molting is ‘like having your lungs ripped out’
When an insect gets too big for its exoskeleton, it sheds it. This process—known as molting—might sound matter-of-fact, but it’s not. Insects stop eating, many lie still, and they become more vulnerable to predators. Now, a study of mayfly larvae has revealed another difficulty: While molting, insects can’t breathe. Alarmingly, the respiratory impairment grows more severe with higher temperatures, suggesting that climate change and other stressors could make molting an even greater challenge.
Aquatic insects breathe with gills. After oxygen diffuses from the water, it passes into a branching network of ever-smaller airways, called tracheoles, which deliver the gas directly to clumps of cells. Larvae can also absorb some oxygen through their soft exoskeleton.
Molting takes their breath away. When larvae slip out of their exoskeleton, the lining of the tracheoles comes with it. “It’s like having your lungs ripped out,” says Joseph Bernardo, an ecologist at Texas A&M University, College Station, who was not involved in the research. Although it was fairly common knowledge among entomologists that the tracheal linings come out—and likely block the trachea in the process—the impact on respiration hadn’t been measured.