The yellow spotted water beetle is a species of diving beetle that can eject a milky fluid from its prothoracic glands when disturbed. This fluid containing a mixture of steroid compounds, presumably as a deterrent to fish predators. They are known in Southern California, Arizona, New Mexico, Texas, and Mexico. Their young, known as water tigers, hatch from eggs laid in sand soil. Just a few weeks after emerging from their pupae, the adults are ready to reed. Their streamlined carapace is jet black, peppered with bright yellow spots. In general, females are slightly larger than males.