Reaching lengths of up to 60 mm, the giant water bug (Lethocerus americanus) is the largest aquatic insect in Alberta. They look like fearsome predators – and they are! With their large raptorial front legs and a long, piercing proboscis (folded between the front legs), they can subdue anything that they are able to wrestle under control, including frogs and small fish. They feed by injecting digestive enzymes into their prey and sucking out the liquefied contents. Giant water bugs are not aggressive but if mishandled, they can inflict a very painful bite. They are best left alone.
Giant water bugs inhabit shallow weedy ponds, wetlands, and the shallow margins of lakes and slow moving streams. Although they spend most of their time lurking along the margins, waiting for unsuspecting prey to swim by, they do have the ability to fly between waterbodies.