Brazos Bend State Park - Pond Life Giant Water Bugs

Pond Life of Brazos Bend State Park

Giant Water Bugs: Family Belostomatidae

Giant water bugs, also known as ferocious water bugs or toebiters, are among the most common, and most impressive water bugs found at Brazos Bend State Park. Although some members of this family are truly giants, reaching a length of 3 inches, these are rarely seen here. The giant water bugs we see most often are a small species, usually about 1 inch long. Their small size notwithstanding, they are fierce predators and will attack animals such as minnows or tadpoles much larger than themselves.

The giant water bug of genus Belostoma, that we see most often in Brazos Bend State Park are chocolate brown in color. They are about 1 inch long when fully grown. Their bodies are flat and wide with a pointed oval shape. The hind legs are large, and are flattened into paddles for swimming.

Giant water bug 25 mm

The hind and middle legs have small double claws on the ends. The forelegs are short but powerful with sharp claws on their ends. The head is triangular, almost frog-like, with bulging eyes. Giant water bugs breath through tubes at the end of their abdomen. These tubes are usually drawn up into their bodies, and not often seen.

Giant water bugs can be found year round in the ponds at Brazos Bend State Park. In cold weather, however, they are usually very sluggish and when found have their legs all folded up beneath them, so that they look like leaves.

The forelegs of the giant water bug are modified into powerful claws that it uses to seize its prey. In scientific terminology, they are said to be raptorial. Like most other hemiptera, its mouth is modified into a long flexible beak that resembles an elephant's trunk, with a bayonet on the end of it. When it stabs its prey with this beak, chemicals are injected into the wound that dissolve the prey's internal tissue. It then sucks the dissolved tissue up through the beak. Giant water bugs should be handled with extreme care, since their bite can be very painful.

Beak and raptorial forelegs of giant water bug

Juvenile giant water bug molting

Like all hemiptera giant waterbugs undergo incomplete metamorphosis. The newly hatched young resemble the adults in almost every respect except the lack of wings, and size. As they grow, they frequently shed their exoskeletons to grow larger ones. The picture at the left shows an immature giant waterbug coming out of its old shell.

The female belostoma attaches her eggs to her mates back in a large pad. Sometimes, it completely covers the male's back. She does this primarily for protection. He will take care of the eggs until they hatch. If however the eggs fall off, he will eat them.

Male Giant water bug with eggs

Giant water bugs are sometimes confused with water scorpions, especially the broad flat species, or with creeping water bugs. Water scorpions do not have the flattened paddle-like hind legs, and can not retract their breathing tubes. Creeping water bugs have a very round head and their eyes do not bulge out from the head like those of the giant waterbug.

Creeping Water Bug

Hemiptera

Updated: Sep 06, 2011