Spider mite males undress females to secure the first mating.

Intense mate competition favors the evolution of extraordinary mating strategies such as the ability of males to identify premature females that are close to becoming mature and associate with them until they are sexually receptive (dubbed precopulatory mate guarding). Owing to possible take-overs by rival males, precopulatory guarding is a high-risk, time- and energy-intensive strategy. Here, we provide experimental evidence that guarding spider mite males undress females by actively removing the exuvia during ecdysis to adult; females undressed by guarding males eclose faster than unguarded females. Such behavior is adaptive because it maximizes the guard's chances of being the first mate.