Giant Water Bug

Scientific name: Lethocerus americanus

Giant Water Bug The Giant Water Bug is the biggest bug in Minnesota -- a full 2-inches long and about 1-inch wide.

This creature is in the insect order known as Hemiptera, or the "true" bugs. The family is Belostomatidae, which consists of bugs commonly known as Giant Water Bugs (not beetles). The species in the genus Lethocerus, as this one is, are our largest belostomatids. So, the Giant Water Bug is as large an insect as you will find in the United States.

Giant Water Bugs are common in ponds and lakes, and less common in rivers. The tend to hang out in the vegetation on the fringes of lakes and wetlands. It is in the vegetation that they look and wait for potential prey.

Giant Water Bug - View from underneathThese bugs frequently leave the water and fly about -- you'll often find them in parking lots around large lights. When people see these bugs they think they're seeing huge cockroaches or beetles. But cockroaches and beetles don't get this big and aren't common around lights.

This particular creature is a predator. It eats small fish, tadpoles, snails, insects and other invertebrates (creatures that don't have a backbone). They feed by catching organisms with their large, powerful, front legs, followed by injecting the prey with a toxin to immobilize and/or kill it. Then they suck the juices out of whatever it is. They are not scavengers -- they like fresh meat.

Giant Water Bugs serve an important role as being the top invertebrate predator, especially in wetlands that don't have fish to control insect populations. Much like lions, tigers and humans, Giant Water Bugs are at the top of their food chain and keep populations of smaller invertebrate from exploding and taking over.

These bugs swim very fast, so you probably won't ever see one in the water. But if you happen to get a hold of a live one, either by catching it in a net or finding one that has left the water and is on land, be VERY CAREFUL to keep your fingers away from its piercing mouth part or "beak" as it can inflict a very painful bite. Its mouth is actually not so much a "beak" as it is a sort of syringe—like a mosquito, but larger and nastier.

Class: Insecta
Order: Hemiptera
Family: Belostomatidae
Genus: Lethocerus
Species: americanus

Coloring page

Giant Water Beetle
Giant Water Beetle
gif or

More info

Want to know more about Minnesota's water? Check out our Water page and find out more about the quality of Minnesota's water.

The bug highlighted on this page was collected by MPCA's Water Quality Lab. This lab samples and analyzes water from around Minnesota.