Giant Water Bugs

Photo of a giant water bug
Venomous
Scientific Name
Species in the genera Abedus, Belostoma, and Lethocerus
Family
Belostomatidae (giant water bugs) in the order Hemiptera (true bugs)
Description

“Giant water bug” perfectly describes the members of this family, as these hefty aquatic insects can reach 2 inches in length. They are brownish with oval, flattened, beetle-like bodies. The clawlike forelegs are adapted for grabbing prey, and the hind legs are long and somewhat oarlike, for swimming.

Giant water bugs, if handled or inadvertently harassed by bare-footed waders, can deliver an excruciatingly painful bite — hence their other common name, “toe-biters.”

During breeding season, females adhere their eggs onto the backs of the males, where they stay in a big flat cluster until the young hatch. These egg-laden males are a remarkable sight.

Size
Adult length: to about 2 inches.
Where To Find
image of Giant Water Bugs Distribution Map
Statewide.
Giant water bugs are common in ponds and sluggish waters that have plenty of insects and small prey. They occasionally resurface, because they breathe air using snorkel-like tubes that extend from their hind end. Strong fliers, they are also called “electric light bugs” because at night they are attracted to artificial lights. Sometimes they are found in swimming pools as a result of these nocturnal excursions. Since they deliver such a painful bite, remove them with a net!
Lie-in-wait predators, giant water bugs typically sit motionless at the bottom of a pond, clinging onto a plant stalk, waiting for another creature to pass by. They have been known to eat all manner of small aquatic animals such as insects and crayfish, but also frogs, fish, and even young turtles and snakes. Like all other true bugs, they have tubelike mouthparts that pierce. In this case, they inject a saliva that paralyzes and digests their prey; the bug sucks the resulting liquid.
This remarkable insect reverses the typical roles in parental care: After mating, the female lays her eggs upon the back of the male, where they remain until they hatch. This way, they are protected from the many aquatic creatures that would otherwise devour them. The male, burdened with the coating of eggs, is no longer able to fly and mate until they hatch. The females, however, often mate again.

People in several Asian countries eat giant water bugs as a delicacy.

The sight of a giant water bug deflating a frog shocked writer Annie Dillard into pondering nature’s seeming cruelty, and she recounts this scene at the beginning of her Pulitzer Prize-winning book, Pilgrim at Tinker Creek.

Humans are not the only species to eat these chunky bugs. Many birds eat them, and fish devour them, too.

Formidable predators, giant water bugs are usually considered beneficial to humans since they eat mosquito larvae.

Media Gallery
Photo of a giant water bug
Members of the genus Belostoma can reach 2 inches in length. Strong fliers, they are also called "electric light bugs" because at night they are attracted to artificial lights.
Jim Rathert
1/5
Photo of a male giant water bug carrying eggs on back
After mating, the female lays her eggs upon the back of the male, where they remain, protected from predators, until they hatch. The egg-laden males are a remarkable sight.
Jim Rathert
2/5
Photo of a giant water bug nymph
Giant water bugs develop full wings for flying upon their final molt. Until then, "wing buds" appear on the sides of the thorax of immature bugs. Most true bugs have wings that develop this way.
Jim Rathert
3/5
Photo showing the beak of a giant water bug
Like all other "true bugs," giant water bugs have tubelike, piercing mouthparts. In this case, they inject a saliva that paralyzes and digests their prey. The bug sucks the resulting liquid.
Jim Rathert
4/5
Photo of a collared water scavenger beetle eating a giant water bug.
This collared water scavenger beetle is feeding on a dead giant water bug.
5/5
Photo of a giant water bug
Photo of a male giant water bug carrying eggs on back
Photo of a giant water bug nymph
Photo showing the beak of a giant water bug
Photo of a collared water scavenger beetle eating a giant water bug.
Similar Species
About Aquatic Invertebrates in Missouri
Missouri's streams, lakes, and other aquatic habitats hold thousands of kinds of invertebrates — worms, freshwater mussels, snails, crayfish, insects, and other animals without backbones. These creatures are vital links in the aquatic food chain, and their presence and numbers tell us a lot about water quality.