Water scorpions are up to 2 inches long and look like walkingstick insects. The head is very long and narrow with a beak-like structure. This insect can puncture skin with its beak and inject saliva which contains both an anaesthetic and digestive enzymes. Normally, the water scorpion feeds on the body juices of other insects, tadpoles, salamanders and fish. It lives on the bottom in the vegetation and organic debris.

The water scorpion has a tail-like breathing tube at the tip of the abdomen which allows it to breath while submerged. It also has 3 pairs of false spiracles below the abdomen which help to gauge depth and to compensate for varying water pressure.