Often called the ‘Jesus bug’ because of its ability to walk on water, the male water striders are not nearly as peaceable as their nickname would have you believe. Male water striders threaten their female partners with death so that they can mate with them.
This isn’t as shocking as it may seem to us humans – sexual coercion is common throughout the animal kingdom. There is no courtship behaviour for this insect species as the male begins the reproductive process by mounting a male or female; males will mount both sexes. If a male water strider mounts a female, the female water strider uses something super handy for dealing with this sort of unwanted advancement: a genital shield.
The genital shield covers the genital opening so that the male can’t forcibly inseminate her. She can choose her mate. But, the male of the species has developed behaviour to counter-act the genital shield. After the male has mounted the female, if the female does not open her genital shield for him, he will begin tapping the surface of the water. What does the tapping do?
Well, it attracts predators from below. And since the female is closest to the water, she will be the one who gets injured from any impending attacks. By tapping, the male water strider is threatening harm on the female, unless she relents and opens her genital shield. And this is why the female of the species tries to stay as far away from the males as they possibly can.
Interested in learning more about the mating behaviours of different plants, animals, and fungi? Check back here for more Mating Mondays.
For more information on insects, arachnids, other terrestrial invertebrates, check out the Spencer Entomological Collection.