Nature: Giant water bugs vicious when it comes to attacking prey

 

Jim McCormac's finger provides scale to a giant water bug/Jim McCormac

Nature: Giant water bugs vicious when it comes to attacking prey

Columbus Dispatch
June 6, 2021

NATURE
Jim McCormac

Once one learns that mammoth insects sometimes called “toe biters” lurk in ponds, a person might be less inclined to wade bare-footed.

Formally known as the giant water bug, Lethocerus americanus, this insect is indeed intimidating. If looks could kill, an entomophobe might keel over on the spot.

Despite online videos overhyping the perils of the giant water bug, they’re fierce looking six-legged marshmallows. In fact, if handled or threatened, the bugs often freeze up and play dead. That’s not to say that caution isn’t warranted if handling one. They can pack a punch.

The giant water bug is a true bug in the order Hemiptera, and like many of its brethren it has a stiff tubular proboscis. If a person is foolish enough to get bit – which would normally entail goading the insect to defend itself – they’ll experience notable pain.

Giant water bugs frequent leaf litter and other plant detritus in the shallows of ponds and other water bodies. While the bug may be conspicuous when high and dry and exposed next to my finger, it’s virtually invisible in its aquatic haunts.

Woe to the lesser creature that happens by a lurking giant water bug. The prey is quickly ambushed by the bug, which swims it down in short order. Victims are seized by powerful forelegs, and the coup de grace is administered via the proboscis.

A chemical cocktail is injected which rapidly immobilizes the prey. Other agents quickly go to work, dissolving its innards. The giant water bug then sucks out the contents via its proboscis, like a grisly milkshake.

Admittedly this is a horrible fate by human standards, but fortunately the bugs cannot do us real harm. However, we can be grateful that giant water bugs are not truly giant, like the size of a lunker muskellunge. Then swimming would be an exercise fraught with peril. Kayakers would be capsized, seized, and reduced to dried husks, their bodies left afloat like gruesome buoys marking the presence of the terrors below.

While giant water bugs can’t kill people, they are a rare case of an invertebrate capable of killing vertebrates. Small fish and amphibians are regularly captured. Crustaceans too, and crayfish are often a dietary staple. Other insects make up the bulk of the prey, though.

Females lay around 100 eggs, and place them on underwater vegetation. The male guards them until hatching, ensuring their safety.

On April 13, John Howard and I were exploring a small lake deep in Shawnee State Forest in southern Ohio. The waterbody was full of red-spotted newts and other interesting aquatic creatures. John saw a giant water bug jet from cover, drew his net like a quick-draw shooter and bagged the beast.

We found another, and were quite pleased with the finds. True to their generally passive demeanor, the bugs played dead while we manipulated them for photos. Once we had our fill of these fascinating creatures we released them back into the depths.

Like most bugs, giant water bugs are capable of flight and that’s how they disperse and colonize new sites. They can be attracted to lights, and occasionally turn up on walls by nightlights. Maybe, if you are really lucky, one will appear at your porch light.

Naturalist Jim McCormac writes a column for The Dispatch on the first, third and fifth Sundays of the month. He also writes about nature at www.jimmccormac.blogspot.com.

Giant Water Bug

A Giant Water Bug, Lethocerus americanus, in repose. This incredible bug is well-named, as we shall see.

John Howard, I and a few others were poking around a small reservoir deep in Shawnee State Forest, Scioto County, Ohio, yesterday. We were admiring many Red-spotted Newts swimming about in the clear water like fish, when John exclaimed "Toe-biter!" The colorful name is a colloquialism for the larger species of water bugs, and it does look like they could put a serious clamp on one's tootsies.

Your narrator's finger provides scale to the Giant Water Bug. They can stretch 3-4 inches. GWB's, as they're known (at least now), are voracious predators. Much of their time is spent hiding among dead leaves in the shallows, awaiting potential prey. If something tasty happens by, the big bug springs to life and rapidly swims down the victim, seizing it with those formidable forelegs.

The soon to be meal is pierced with a syringe-like proboscis, and various compounds are injected which debilitate the victim and turn its innards to mush. The contents are then sucked back through the proboscis; a homicidal maniac's milkshake.

While this big bug can inflict a painful bite to people, one would have to work hard or be rather foolish to receive a bite. John was handling the water bug to set up some photographs, and it was quite docile. He of course was cautious about getting near the mouthparts. I'm sure if incautiously handled, a foolish person would indeed get a jab that they would long remember.

The business end of the Giant Water Bug. Not a face you'd want to see headed your way, if you were reasonably small and aquatic.

In a rare case of invertebrate turning the tables on vertebrates, Giant Water Bugs can seize, kill and eat smaller members of the backboned crowd. They'll capture small fish, amphibians, and even small snakes. Remarkably, heavily armored and also formidable crayfish are sometimes taken.

It's quite fortunate for us humans that these things are not the size of large carp, or we'd probably be a course on their dinner plate.