Lethocerus americanus is a giant water bug in the family Belostomatidae, native to southern Canada and the United States . It typically has a length around 5-6 cm . It was originally classified as a species in genus Belostoma.

Commonly found in ponds, marshes, and on the edges of lakes and slow-moving streams, adults and larvae feed on other insects, small crustaceans (crabs/crayfish), tadpoles, snails, and small fish. The adult swims with the aid of its hind legs. A pair of front fore limbs is used for capturing and latching onto its intended prey, which it then injects with digestive toxins through a somewhat retractable proboscis much like that of a mosquito. L. americanus tends to let its prey digest for 10-15 minutes before eating. Multiple L. americanus bugs have been seen to hunt and then share the same prey animal. Under water, the adult breathes air that it traps under its wings using two snorkel-like tubes that extend from the rear of its abdomen.

Giant Water Bugs, and their nymphs, are fierce predators feeding on small fish, tadpoles, salamanders, even small frogs. They usually hunt by lying-in-ambush clutching a submerged plant or rock with only their breathing tube sticking above the surface. Any passing motion can trigger a rapid "lunge and grab" with the hook-tipped front legs. If prey is successfully grasped it is quickly dispatched with a pierce from the bug's needle-like rostrum (fused mouth parts) and an injection of toxic enzymes. These enzymes poison the prey and begin to digest it at the same time. Once the enzymes have completed their job the bug again uses its rostrum, but this time sucks out the pre-digested soup that was its prey, leaving a limp bag of skin. If this critter sounds like some kind of mini-monster, don't despair. In the orient, giant water bugs are renowned as a great delicacy, so, as always, critters seem to have more to fear from us than we from them.

Commonly known as "toe biter", L. americanus may deliver a painful bite if handled or disturbed. However, it prefers to avoid humans rather than engage them whenever possible. If disturbed in the water, the speed of L. americanus allows it to quickly break away while its natural camouflage easily conceals it. Even if agitated on dry land, L. americanus will first attempt to escape or play dead before raising its fore limbs and hind quarters in what resembles a fighting stance. If agitation continues, L. americanus will use its fore limbs to latch onto the source of the agitation and attempt to deliver a painful bite. Also known as the "electric-light bug", it may be attracted by electric lights while flying at night.

Eggs are laid on vegetation located at the water's edge and may be guarded by an adult. The young nymphs then hatch about two weeks later.Unlike giant water bugs in the subfamily Belostomatinae, females do not lay the eggs on the backs of males. Instead, after copulation (often multiple sessions) the eggs are laid on emergent vegetation (rarely on man-made structures) high enough above the waterline that the eggs will not be permanently submerged. The male then guards the eggs from predators and periodically brings water to the eggs to prevent their desiccation.

Like other members of the giant water bug family, Lethocerus species are predators that overpower prey by stabbing it with the rostrum and injecting a venomous saliva. The rostrum can also be used in self-defense, and the sting is very painful to humans, but usually resolves within a few hours at most