Water Bugs: What to Know

Medically Reviewed by Jabeen Begum, MD on January 20, 2023
5 min read

The giant water bug is a predatory insect that hunts aquatic creatures. This bug has sharp mouthparts that deliver a painful bite to prey and humans. Many people call the giant water bug a “toe biter” because it can attack the feet of unsuspecting swimmers. Find out what you need to know about water bug characteristics, habitats, and how to remove them. 

Giant water bugs are freshwater insects that belong to the family Belostomatidae. Over 60 species of water bugs exist worldwide, and 20 of these species live in North America. 

What do water bugs look like? The giant water bug looks like a hybrid cockroach and praying mantis. It has a brown, flat body with clear, lacy wings that harden at the base. The insect’s most distinctive features are two large front legs that resemble pincers. It uses these powerful limbs to grasp and subdue prey. 

All Belostomatidae insects have cylindrical, needle-like beaks for biting and eating. The giant water bug’s bite injects poisonous digestive enzymes into prey. These compounds paralyze the victim and liquify muscles and tissues. The giant water bug sucks this fluid out. 

This aquatic insect has breathing tubes near its abdomen that function as snorkels. These tubes reach up to the surface and capture oxygen, which the giant water bug stores in a bubble under its wings. The bubble passes air into the water bug’s body through abdomen holes called spiracles.

The giant water bug’s size varies by species. The Lethocerus americanus species is the biggest true bug in the United States and can reach 4 inches long. Other species average around 1 to 2½ inches long. 

Can water bugs fly? The giant water bug flies between habitats. You may also spot water bugs flying around porch lights, streetlights, and other lights at night. 

What do water bugs eat? The water bug is an ambush predator that lurks in plants near the surface of ponds and streams. It snatches passing prey with its strong pincers and immediately injects its poison. This mighty hunter can snare and feed on creatures up to 50 times larger than it.

The giant water bug’s diet includes crayfish, insects, fish, and frogs. It can even eat juvenile snakes and turtles. 

What is the water bug life cycle? Water bugs have elaborate mating rituals that involve underwater dances and sparring. Females in the Lethocerus genus lay their eggs on vegetation above the surface of the water. By contrast, females in the Abedus and Belostoma genera deposit eggs on the backs of male water bugs. The males protect the eggs from predators and carry them until they hatch.

Eggs hatch in one to two weeks, and juvenile water bugs mature in one to two months. The water bug’s lifespan averages around one year.

Dozens of giant water bug species exist worldwide, but you may only encounter one or two types depending on your location. Here are a few species:

  • Lethocerus americanus. You can find this giant water bug throughout most regions in North America. This insect lives in creeks, marshes, ponds, streams, and other bodies of water. It survives the winter by living in mud.  
  • Lethocerus indicus. This water bug lives in Taiwan. Humans often cook this insect in sauces or steam it and eat it as a delicacy. 
  • Lethocerus uhleri. This species has striped middle and hind legs. It lives in many regions of North America, including Canada, the eastern United States, and Mexico.

Water bugs live across the United States and other areas in North America. You can find various species in Georgia, Florida, Kansas, Maine, Mississippi, Nevada, Texas, Utah, and many other states. 

These insects typically live in slow-moving bodies of water filled with aquatic prey.  Water bugs can also fly into swimming pools and gather outside residential areas with bright lights.

Giant water bugs generally don’t enter homes, but you may notice them in your pond or swimming pool. They often hide under vegetation below the surface of the water. 

Many people confuse giant water bugs with cockroaches. You can tell the difference between these two insects by looking for antennae. Cockroaches have long antennae, while giant water bugs have none.

Standing bodies of water like ponds and puddles can attract aquatic water bugs to your yard. And leaving bright outdoor lights on at night can cause water bugs to swarm outside your house. 

Giant water bugs can harm humans and pets with their venomous bites. 

Do water bugs bite? A giant water bug can bite you if you pick it up or accidentally step on it. This bite can cause extreme pain, but experts typically don’t consider this injury medically dangerous.

Symptoms of a giant water bug bite include: 

  • Intense pain
  • Mild to severe swelling of the affected area
  • Tingling in the bitten limb 

In rare cases, a giant water bug bite could cause an allergic reaction leading to difficulty breathing, hives, and itching. Seek medical treatment if you experience these symptoms after a bite.

Most water bug bites resolve within five hours without medical intervention. At-home methods to treat water bug bites include: 

One case study reports that taking antihistamines didn’t relieve symptoms.

You can get rid of giant water bugs by replacing blue outdoor lights with yellow lightbulbs, which are less likely to attract these insects.

You can prevent giant water bugs from entering your home by sealing off cracks and holes in siding and window screens. A pest control professional can also help you eliminate giant water bugs.

While many consider the giant water bug a dangerous nuisance, this insect benefits humans by eating mosquito larvae. If you find giant water bugs living in ponds and other natural bodies of water, consider keeping your distance and leaving these fascinating predators alone.