The defensive chemical cantharidin for which the beetle is known is produced only by males; females obtain it from males during mating, so it may be a nuptial gift, increasing the value of mating to the female, and thus increasing the male's reproductive fitness.
The defensive chemical cantharidin for which the beetle is known is produced only by males; females obtain it from males during mating, as the spermatophore contains some. This may be a nuptial gift, increasing the value of mating to the female, and thus increasing the male's reproductive fitness.