Monster bug

Giant Water Bug

Yesterday I returned to my parents’ for a couple of days, and took advantage of the warm weather last night to try for some moths. There’s a great diversity of habitat here, with a mature mixed forest on one side, open scrubby areas to another, of course the wet swamp in the corner of the property. So I was hopeful for some good stuff, and I wasn’t disappointed. That all will be the subject of another post. I’ll be setting up again tonight (I head back home tomorrow), to hopefully add to the list.

I ran my new trap overnight, but I also put out a sheet and blacklight. I got a number of species at the blacklight that didn’t show up in the trap, and some nice ones among them. However, the most interesting thing to come to the sheet last night wasn’t a moth at all. Most of the time I just glance over the beetles and wasps and midges (I can only focus on one taxon at a time, and currently it’s the moths). But I couldn’t ignore this guy. I was leaning forward investigating some moth on the sheet when a very loud buzzing whirr whizzed by my head and flopped on the ground in front of the sheet. Out of the corner of my eye I thought it was a sphinx moth or something big like that, but when I stooped to investigate, it most definitely was not. My second impression was of a cockroach, since it had the same dorso-ventrally flattened body.

Giant Water Bug

But it’s neither. In fact, this is a Giant Water Bug, also called Giant Electric Light Bug, after its habit of coming to artificial lights. It was rather alarming in its size and apparent ferocity. Fortunately, the same features made it very easy to identify. I got a clear plastic container and brought it inside to show my mom. She joked that she wasn’t going outside at night again.

Giant Water Bug

It’s about 6cm (or 2.5″) in length, with these giant broad modified front legs that it uses to secure its food. As its name indicates, it’s an aquatic insect, primarily, associated with swamps and wetlands. Normally it lives in or near the water, preying on aquatic insects, but supplementing this diet with opportunistically-caught vertebrates such as frogs or small fish. It uses a tubular rostrum to suck out the body fluids of its victims. It can inflict a painful bite, and so also has the name “Giant Toebiter”, which I would assume dates back to the days when kids were more likely to wade into mucky water barefoot (I used to do that as a kid, carefree about the creatures inhabiting it; I’m more cautious now, but it’s more because of concerns over submerged or buried sharp things, especially glass or metal garbage).

Giant Water Bug

Check out the giant eyes, which it obviously uses in stalking its prey. Plus the giant single claws at the end of each leg. I’m not sure what the white goop on its one eye is. The bugs are found across North America; there’s actually three species that are similar in appearance (I’m not sure which one I have here), and which overlap in range. Young look similar, but are obviously much smaller and take smaller prey. It takes them five moults to reach adulthood, which they do in a season; they overwinter buried in the mud as an adult. This site suggests that adults are edible, but I’m not sure I’d find them much of a delicacy.

Mites on a Giant Water Bug

When I copied the photos to my computer and looked at them closely, I discovered that the bug had been carrying what I took to be mites. You can also see a couple of large ones in the second photo, where it has its wings spread. I have no idea what species they are, or even if they are really mites, and not fleas or some other parasite like that. It seemed to have a good infestation going.

It’s amazing how it’s possible to overlook something that you would think would be quite obvious. If it comes to lights, why have we never seen it at the porch light? And being so large, you’d think we would have noticed it one of these times when down poking around the ponds. But it somehow escaped our notice to now.


Author: Seabrooke

Author of Peterson Field Guide to Moths. #WriteOnCon Mastermind. Writer of action/thriller SF/F YA. Story junkie. Nature nut. Tea addict. Mother. Finding happiness in the little things. Twitter: @SeabrookeN / @SeabrookeLeckie

26 thoughts on “Monster bug”

  1. It’s not a moth– it’s a behemoth!

    Nice, detailed pictures.

    I have a few times found them dead in parking lots. Apparently they mistake car windows for standing water.

  2. I wouldn’t want to step on that while barefoot. Your macro pictures are excellent. Gives a different perspective to something most people would dismiss as gross. I truly would have thought it was a cockroach.

  3. I really like how your close-ups keep getting closer, and your text answers the viewer’s “Hey, what’re those red thingies on the edge of its carapace?” questions.

  4. Very cool, I’ve never seen one flying but have caught them in pools! Sea World Ohio (now defunct) used to have a tank of dozens of these creatures, and I seem to remember that they raised young nymphs on their backs!


  5. I was wondering about their young, too.
    I know I’ve seen them carrying eggs on their bodies–could those small things be young?

  6. Great pun, Hugh! It’s funny I’ve never encountered them before, I read that they’re often seen near streetlights, too.

    Ruth: It certainly does make me think about all those times I waded around in the muck as a kid. Apparently there’s leeches in our ponds, too, and I never happened to encounter those, either.

    Thanks, Lavenderbay. I do try to write in a sort of photo-journalistic fashion that would keep someone reading to the end of the post – or that’s the hope. :)

    Tom and Nina: Yes, one of the species does actually lay its eggs on the back of the male, who helps to aerate them by water passing over them while he swims. The other species lays its eggs on vegetation at the water’s edge (may or may not be submerged). I’m not sure which species this one is.

  7. Greetings,

    Yes, these insects are definitely edible. Both Lethocerus [the genus to which your specimen likely belongs] and the other Belostomatids are avidly consumed in several Southeast Asian countries; I also serve them to the public in Rhode Island and elsewhere as part of the insect tasting events I run through my company, Sunrise Land Shrimp — because insects are the shrimp of the land. Or water, in the case of this particular bug.

    Unlike other insects that are eaten whole, this one I filet; there’s actual meat in the thorax, the muscles that power the wings. The meat is surprisingly fruity and smells sort of herby/perfumy, and people are shocked at the taste of it! I get mine frozen from Thai markets here in Providence, but I’ve also sampled wild-caught specimens from Louisiana.

    Anyone interested in more details is invited to contact me.

  8. Thanks for the great info, Dave! Whoda thunk they’d make such good eating? It’s funny how recent culture has turned insects into such a distasteful food item, when really there’s nothing wrong with them. Next time I’m in Rhode Island I’ll have to check your place out!

  9. cool site and pics, always thought these giant water bugs were cool, growing up in winnipeg manitoba, there were several years when the streets would be covered with them and the boys would be mean and drop them into little girls hands.


  10. Thanks so much for the detailed information, and the SPECTACULAR close up photos! I regularly catch these horrid looking things in my pool… (Qld, Australia). At least now I know what they are!

  11. I captured a Letocerus Americanus 2 weeks ago and try to keep it alive. But I noticed that it carries some parasites on it back, a bit like those mites that you show on the pics.

    Should I try to remove thoses mites? Is it possible to do withiout hurting the Lethocerus?

    1. I don’t think the mites will hurt it, you can probably leave them there and the bug won’t be bothered. I’m not sure whether the mites are parasitic (eg. feeding on the bug’s “blood”) or symbiotic (eg. feeding on bacteria or other smaller stuff on the bug, like oxpeckers cleaning bugs off of water buffalo in Africa), but I suspect the latter.

  12. After encountering one of these the other night, I have done a great deal of research. I am almost positive that the “mites” on its back are actually newly hatched young.

  13. I tried to remove one of them from the back of the lethocerus, but it’s simply impossible. So I decided to leave the mites on it. Since, I see 2 of them quit the back of the insect and swim in the water surronding the bug. It looks like some kind of hydracarina. I change the water and kill the hydracarina when I see one of them swim around the lethocerus…

    I hope to reduce the quantity of mites on the back of the insect by this way.

  14. It’s dead…. My lethocerus is dead… :-(

    I don’t know how long a lethocerus can live, but this one lives for 2 mounts (that a long time for an insect!!!).

    A great experience to keep it alive, an it was amazing to see it chase small fishs.

    I’ll hope to find another specimen in the future…

  15. Very nice photos!

    Giant water bugs are amazing animals. I regularly found them in some California ponds. Interestingly, there was a lot seasonal variation in whether they were infested with mites or not. Some times of year the adult bugs were covered with mite, and other times I couldn’t find any mites on them.

    I’ve also seen a smaller genus (Belostoma) that have had freshwater limpets attached to their back. I’ve wondered if these Belostoma could fly with the limpets attached.

  16. A friend who knew I was into ‘bugs’ sent me one once, via several friends and hand-offs. I saw it burrowed in the bottom of a dry coffee can full of grass, and said ‘it’s a waterbug!’ The poor thing, nearly dessicated, came back to life when I added a little tap-water.
    I kept it for about 6 months, buying it ‘feeder fish’ from the pet store, but got to feeling bad about the fish, after watching it dig its snout into their eyeballs and suck out their juices a few times… to I let it go in an Audubon Sanctuary stream, and kept the ‘feeder fish’ for the next 10 years.

  17. This is my first time visiting your site! I came across it looking for info on the Dobson fly, which had been a mystery bug 2 me, for the past to Summers.

    I am totally hooked on your site now, can’t wait to see more!!

    Wow didn’t know water bugs bite! By the looks of them, it would hurt!

  18. It was just a few weeks ago after a storm, I came home from work and my breeze way had about 6 of these things flying around. I was so freaked. Since then without fail, every other night or so there is anywhere between 3-5 out side my door. I don’t really share your enthusiasm. I wish they would go away.

  19. We live in the upper region of the Oregon coast. Have never ever seen one of these before. Until last night, it was as big as a small humming bird! Although I felt that it wouldn’t hurt myself or my boyfriend, it still freaked me out as it would fly by close to get to any loight source.
    Thank you for the picture, it helped us identify what it really was!

  20. Found one of these on a pool float today and thought it was a giant leaf that fell off the float and fell to the bottom of the pool after i picked the float up..until it began RUNNING on the bottom of the pool! It ran and walked the entire pool, swam to the surface, dove to the bottom again and swam around. I that scary beast out and was on edge the entire outing. When I got BBC back inside I found and read your article and realized it could actually bite–painfully! I also read it injects venom too, though not deadly to humans thankfully. I will be very careful now since I often swim with my 4 year old grandson! Thanks for this helpful article!

Leave a Reply to Jessica Cancel reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: