This crazy looking bug is a giant water bug, Abedus herberti. They are found in pools of freshwater in the mid-west to southwestern region of the US. This is a male water bug, as females lay eggs on the backs of the male carapace. Matings are cyclical, where a female will only be allowed to lay a few eggs on a male's back before having to mate with him again. This will ensure that the males aren't brooding eggs fertilized by another male. This is particularly effective as genetic markers show that the last male's sperm has precedence in fertilization over any stored sperm .
The males take care of the eggs until they hatch. This includes spending more time on land, to keep the eggs from getting fungus. I would be interested in knowing what traits females are selecting for when they choose their mates.