KINGDOM: Animalia | PHYLUM: Arthropoda | CLASS: Insecta | ORDER: Hemiptera | FAMILY: Belostomatidae (giant water bugs)

Giant Water Bugs are in the order Hemiptera which also includes assassin bugs, stink bugs, and many other insects.  All insects in Hemiptera share a few characteristics, including piercing and sucking mouthparts, and wings which are membranous and clear at the tips, but hardened at the base.

Giant water bugs have a unique appearance and are difficult to confuse with most other kinds of insects.  Resembling a cross between a cockroach and a praying mantid, giant water bugs are brown and flat with large, raptorial (prey-grasping) front-legs.  There are a few species of the closely-related water scorpions (family Nepidae) that resemble giant water bugs, but water scorpions always have a long, non-retractable breathing tube at the ends of their abdomens.  Giant water bugs have a breathing tube as well, but it is much shorter and is usually retracted into the abdomen.

Raptorial front legs of a giant water bug (B. Newton, 2002)

Although some giant water bugs are very large (over 2 1/2" long), not all species in this family are giants.  In fact, the most commonly encountered giant water bugs in Kentucky are only about 1" long.

Like all members of the order Hemiptera, giant water bugs go through a simple metamorphosis with egg, nymph, and adult stages.  During warm months, female giant water bugs attach eggs to underwater vegetation or (in some species) stick eggs to the backs of males.  In these species, the male will carry the eggs until they hatch.  After hatching, the wingless nymphs resembled small, wingless adults.  They molt several times before becoming full-sized, winged adults.  Large nymphs or adults are usually the overwintering stage.  All stages are aquatic.

Giant water bugs are aquatic predators that are found in ponds, slow-moving streams, and wetlands in Kentucky.  They feed on many aquatic vertebrates and invertebrates, including minnows, tadpoles, frogs, and other aquatic insects.

Giant water bugs are primarily ambush predators who wait with front legs outstretched in aquatic vegetation near the water surface.  When a meal swims too near, the giant water bug grabs it and pierces it with its sharp beak, quickly injecting it with paralyzing fluids and digestive juices.  Although giant water bugs are fierce predators, they are often eaten by fish and larger predatory insects and spiders. Shown below is a giant water bug feeding on a cricket.

Giant water bugs are not considered pests, but their bites can be painful.  Some people exhibit medically serious reactions following a bite from a giant water bug, but this is very rare.

LETHOCERUS sp.
GENUS: Lethocerus
At over 2" in length, giant water bugs in the Lethocerus genus are the largest in the Family Belostomatidae that occur in Kentucky.  Lethocerus water bugs occur in Kentucky, but they are much more common further south.

BELOSTOMA sp.
GENUS: Belostoma
Giant water bugs in the Belostoma genus are very common in Kentucky.  These water bugs are normally 1" long as adults and are frequently found in ponds and slow-moving streams.  Other than their size, they look very similar to the Lethocerus water bug pictured above.  Excellent pictures of Belostoma water bugs are posted at the Cedar Creek Natural History Area Home Page from Minnesota:
http://cedarcreek.umn.edu/insects/album/020037003ap.html

Giant water bugs can usually be found in weed-choked ponds and sluggish streams during warm months.  An aquarium net or aquatic dip net is needed to capture them.  Like many aquatic insects, the best way to capture giant water bugs with an aquatic net is to repeatedly dip the net in the water and examine the contents, rather than trying to visually locate the bugs and capture them one by one.  Remember: giant water bugs can bite, so they should not be handled.

Aquatic insects can be very difficult to photograph without expensive underwater cameras.  However, because giant water bugs breath air, they can be brought to the surface for a quick picture.  Giant water bugs, especially the large ones in the Lethocerus genus, will often remain still on a piece of aquatic vegetation even after it is pulled out of the water, making for an excellent photo opportunity.

Giant water bugs will also thrive in a freshwater aquarium as long as a perch (in the form of fake or real aquatic plants) is provided.  For large Lethocerus water bugs, drop a few large guppies or other small fish into the aquarium once a week, or offer the insect large crickets with a pair of tweezers.  Smaller belostomatids will eat tadpoles, small guppies, small crickets, or other small aquatic prey.

Because giant water bugs sometimes fly to lights at night, they are often called "electric light bugs."

Do you know any myths, legends, or folklore about giant water bugs?  Let us know if you do!