The giant water bug is the largest aquatic insect in Quebec. Its flat, hydrodynamic body and the long hairs on its middle and back legs make it a fast and efficient swimmer. It has large compound eyes on its head. It eats using piercing-sucking mouthpieces that form a sort of short, pointed beak, called a rostrum, under its head. It has a short respiratory tube at the end of its abdomen that consists of two flexible, retractable parts that can move back and forth.
Water bugs are Hemiptera with an aquatic lifestyle. Some of them, such as the giant water bug, water scorpion, water stick insect and water strider, are voracious predators. Others, such as the back swimmer and the water boatman, feed on algae and plant particles.
These bugs, like all Hemiptera, have back wings with thick, opaque tips that are more membranous than the wing base. Some of them, like the giant water bug, have a special appendage at the base of their wings that allow the insect to keep its wings tightly closed against its body. This adaptation to aquatic life makes the insect a better swimmer.
Water bugs undergo an incomplete metamorphosis. The newly hatched insect looks like a smaller version of the adult without wings, and generally lives in the same environment, feeding on the same prey.