Female sagebrush crickets (Cyphoderris strepitans) munch off males' wingtips during mating (pictured), stimulating an immune reaction that saps males' energy and makes it harder for them to woo other females.
Scott Sakaluk and his students at Illinois State University in the town of Normal arrived at this conclusion after measuring the cost of the immune response to male sexual vigour. They injected some wild-caught virgin males with lipopolysaccharides that trigger their immune systems, and others with a substance that has no such effect.
Lipopolysaccharides drastically reduced the courtship behaviour and mate procurement of male sagebrush crickets. Females seem to gain nothing more than a good meal from this act of aggression.