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.
Body length up to 2 1/2" long
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
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.
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.
KENTUCKY GIANT WATER BUGS
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.
Water Bug in the Lethocerus genus (B. Newton, 2003)
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
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
WATER BUG FACTS
Because giant water
bugs sometimes fly to lights at night, they are often called "electric
- LEGENDS - FOLKLORE
Do you know any myths,
legends, or folklore about giant water bugs? Let us know if
Original document: 25 May 2004
Last updated: 25 May 2004
Photos courtesy R. Bessin and B. Newton, University of Kentucky
The Kentucky Critter
Files are maintained by Blake Newton, Department of Entomology, University