Giant Water Bugs Eating

I didn’t post anything last week because I was in the midst of chaos with family and friends, making final preparations for my wedding last weekend.  But now I’m back at the computer and getting things done!  Since I just took a short break, I thought I’d take this opportunity to express my thanks to everyone who’s been keeping up with my blog.  I appreciate your comments and your support!  It’s gratifying to know that something I enjoy doing so much is informative and helpful to others.

Lethocerus indicus eating a small fish

Lethocerus indicus eating a small fish

Today I thought I’d post a short video that illustrates how giant water bugs eat.  Giant water bugs are fierce predators and are known for being able to take down very large prey such as snakes, fish, turtles, and even birds!  Even more amazing is that they accomplish these feats while they barely move at all!  Giant water bugs are called sit and wait predators.  If you think about that phrase for a moment, the behavior it describes should become obvious: giant water bugs sit in one place and wait for prey to swim by.  As much as I love giant water bugs and try to get people excited about them, I’m the first to admit that they sit in one place for long periods of time without moving at all.  In fact, they can even be a bit boring to watch at times.

Abedus herberti

A giant water bug in the pose they normally adopt while waiting for food to swim by.

However, any boredom instantly disappears if the giant water bug you’re watching encounters food!  Part of what makes them exciting to watch is their structure.  I wrote about how to tell the American giant water bug genera apart several months ago and talked about the raptorial forelegs that giant water bugs possess.  Most of the time, you’ll see giant water bugs sitting underwater, holding onto a rock, the bottom of the pond or stream, or a piece of vegetation with only their hind two pairs of legs.  The front legs, those strong raptorial forelegs, are held in front of them, as in the photo above.  If food swims by, they thrust those muscular forelegs forward very rapidly, fold the legs over the food, and then retract their legs back toward their bodies, bringing the prey close to their heads.

The giant water bug then begins to eat its food.  First, it has to find a place it can insert its piercing-sucking mouthparts, that beak that you can see hanging off the front of the head of the bug in the image above.  It will probe the prey item with its beak until it finds a soft place into which it can insert its mouthparts.  The water bug then injects the prey with chemicals that break the tissues down, turning them into a sort of soup.  Finally, the bug sucks the liquid out of the prey and into its own body.  This part is rather like what you do when you take a drink or eat a smoothie with a straw!

Depending on the size of the prey item, the eating part of the process can take a very long time, up to 10-12 hours.  It takes a long time to inject all those chemicals and suck up the resulting soup.  But the prey grabbing happens VERY fast!  So fast that most prey items probably don’t even see the bug before it’s too late.  And so fast that the very first time I fed a bug as a graduate student, I dropped the forceps in which I held the prey (a mealworm) and jerked my hand out of the way as hard as I could.  There may or may not have also been a loud girlie shriek involved, one that I may or may not have been very happy that no one else was in the lab at the time to witness.  :)

So, to get an idea of just how fast water bugs are when they grab food, I recorded my lab bugs the last time I fed them.  Without further ado, I give you a giant water bug (species: Abedus herberti) eating a mealworm!  Pay special attention to how fast the bug grabs the mealworm.  If you look closely, you can also see it probing the mealworm with its beak!  Look for the probing in the space between its eyes and its left foreleg:

Pretty cool eh?  That speed and power in their forelegs allow giant water bugs to catch and eat some very large things.  How amazing is it that an insect, and an aquatic insect at that, can capture and consume a bird?!  And I’m not talking about little birds either.  There is a published report of one taking down a woodpecker.  Now that’s just impressive.

I should be back to my usual posting schedule now, so look for a new post next week!  I’ll be installing an educational aquatic insect pond at the Biosphere II soon, so I’ll be posting about that for sure.  But first, another quick video, this time of a non-insect aquatic invertebrate: the flatworm!


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