The Carlisle Mosquito Online

Friday, November 3, 2006


Giant Water Bug, aka Toe-Biter and Electric Light Bug

While checking on our green frogs in our backyard fish pond on October 22, my granddaughter Elisabeth caught a huge bug in her net. Usually interested in creatures, she let out a shriek when she reached in the net and encountered this large mysterious bug. "Looks like a cockroach," was one adult comment.

Further research identified it as a Giant Water Bug, Lethocerus americanus, about the largest true bug (Order Hemiptera) found in the U.S., and no relation to cockroaches, but a close relative of stink bugs. It frequently leaves the water and flies about.

This bug, shown actual size (depending on your screen resolution), is over two inches long and a full inch wide and has piercing and sucking mouthparts which you should avoid. (Photo by Susan Emmons)
Description. This bug is over two inches long and a full inch wide and has piercing and sucking mouthparts which you should be very careful to avoid. Fortunately our bug was sluggish from the cold water or "playing dead" which it is known to do, so no one got bitten. It quickly became very active and after being photographed, even though it had been wrapped tightly in the net, escaped. It belongs to the family Belostomatidae, meaning arrow-mouthed.

It has powerful raptorial (prey-grasping) front legs and flattened, fringed hind legs adapted for fast swimming. The body is flat and elongated, which gives it the appearance of a flattened cockroach.

Breathing. This bug has a breathing tube for taking in air, which helps explain why it is found in ponds. This tube-like appendage is at the posterior end. A bubble of air is stored under the wings while the bug is swimming underwater. The air tube is usually retracted, unlike the tube of its close relative, the water scorpion.

Habitat and Behavior.The usual habitat is ponds, quiet streams and swamps and unsuspecting waders sometimes get a taste of their painful, but rather harmless (to humans) bite, hence the "toe-biter" name. The bug tends to hang out on vegetation at the water's edge, or lurk on muddy bottoms, waiting to pounce on its prey, which consists of small fish, snails, frogs and aquatic insects. Using its powerful front legs, the Giant Water Bug catches its prey and then pierces it and injects a toxin to immobilize or kill its catch, so it can suck out its juices. These predators help keep some insect populations under control. We also wonder if it was the predator that ate some of our smaller fish, although we also suspect an enormous bullfrog, which came to visit.

Farther south in the U.S., these bugs are very common. While we only had the excitement of dealing with one Giant Water Bug, a few years ago in New Port Richey, Florida, hundreds of these giants flocked to a well-lighted shopping plaza and covered the ground and floors of stores! These bugs are attracted to light (or some references say "confused by light") and hence one of its nicknames, Electric Light Bug.

References. Field Book of Insects by Frank Lutz, Audubon North American Field Guide of Insects and Spiders; American Insects by Ross Arnett. The Internet has dozens of references and the Giant Water Bug is the featured Bug of the Month on the Minnesota state web site:

2006 The Carlisle Mosquito