Friday 5: Keeping Water Bugs in the Lab

I work with giant water bug eggs and need to know the exact date they were laid, so I need to keep bugs in the lab.  This means I need to keep my bugs alive!  Giant water bugs can live well over a year, so you need to have space and time to care for them if you’re going to bother.  That said, giant water bugs are incredibly easy to care for!  Here’s what I do for the back brooders that I use for my research.

Step 1.  Collect bugs in the field.

Me collecting in Florida Canyon

Me collecting in Florida Canyon

I have several places I like to collect giant water bugs.  One sire is part of the University of Arizona, the field research station for the Santa Rita Experimental Range at Florida Canyon.  (That’s pronounced flor-EEEEE-dah, by the way.)  There’s a great little pool, pictured above, located just downstream of the parking area.  All I have to do is take my trusty soup strainer down and scoop bugs out.  Transporting bugs back to the lab is the most tricky part of caring for them in the lab.  They’re aquatic insects, but they rely on surface air and they drown more easily than you’d expect.  You have to be very careful about how much water they’re sloshing around in.  Water bugs are also rather cannibalistic, so it’s best to keep them separated.  I usually place 2-3 bugs in a plastic bag with some wet vegetation gathered from the stream, then fill the bag with air before I seal it.  Then I pack a whole bunch of bags into a cooler.  Seems to work pretty well as I rarely end up with dead bugs, even if I have to leave them in the bags for a day or two.

Step 2.  Introduce bugs to their new home.

Keeping the bugs separate is important, so I use a system my advisor developed:

water bug housing

Water bug condo!

Plastic Rubbermaind boxes make great containers for back brooders!  Inside the box pictured here are a couple of little plastic blocks (not visible) that hold a sheet of plastic pegboard off the bottom of the box.  Bugs are placed in individual plastic drinking cups.  There’s a 1/2 inch hole in the bottom of each cup and each contains a small rock or cement block to give the bugs something to hold onto.  I fill the box so that the water in the cups is about an inch deep.  I can keep 15 bugs in each box without having to worry about them eating each other, so I can keep quite a few bugs in minimal space.  It’s a great system.  Wish I could take credit for it, but it was in place before I arrived and it’s all my advisor’s doing.

Step 3.  Feed bugs.

Belostoma micantulum

Belostoma micantulum eating a mealworm.

Feeding the bugs is important.  They need to eat to live of course, but if they don’t get enough to eat, they don’t produce eggs and I can’t do my work.  Giant water bugs are also predators, so you’ve got to feed them animals.  So, I feed my bugs mealworms once a week.  Mealworms don’t move around much so the water bugs sometimes have a hard time recognizing them as food.  Using a pair of forceps, I dangle a mealworm in front of a water bug and shake it around a bit.  Usually the bugs will grab it right away and slowly eat it over several hours.

Step 4.  Change the water.

Changing the water eliminates any wastes the bugs produce.  Using the pegboard setup makes cleaning the containers is a breeze!  I just take the lid off, pull the sheet of pegboard out with all the cups sitting on top, and set it on the lid.  All the water drains out of the cups as you lift the pegboard.  Then I simply dump the water in the sink, refill with water that’s been sitting out for a few days to remove the chlorine, and put all the stuff/bugs back in!  You can easily clean 15 bugs in less than a minute.

Step 5.  Mate the bugs to get eggs!

giant water bugs mating

Giant water bugs mating (Abedus herberti)

Mating back brooders is incredibly simple.  I’ve talked about how they mate in a previous post, but I didn’t discuss how I set up their mating chambers.  It’s so easy!  All you need are a few plastic bowls with lids (drill some holes in the lids so the bugs can breathe!), one medium sized rock to go in each bowl, and enough dechlorinated water to fill the bowls about 2 inches.  Then you just place two well-fed bugs (a male and a female that have not been mated for at least three weeks) into the container, snap the lid on, and leave them overnight!  Most of the time you’ll come back the next morning to freshly laid eggs.  Sometimes you don’t and have to futz about a bit to get them to lay, especially during the winter, but most of the time you just get a male and a female together and let them go at it.

And that’s it!  Caring for water bugs.  Easy as pie.  Well, easier actually.  Pie can be rather tricky to make.

Posting might be a little light next week!  Got things to do and people to see that might interfere with blogging, but I’ll be back to my regular schedule soon.  Have a great weekend everyone!


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17 thoughts on “Friday 5: Keeping Water Bugs in the Lab

  1. Very informative post!

    We kept a number of Belostoma flumineum in my lab last year for experiments on predator-induced plasticity in aquatic snails. This year we plan to try to get a colony of breeding B. flumineum going.

    Have you tried keeping and breeding Belostoma on a diet composed primarily of aquatic snails? Our bugs seemed to do well on the snails, and appeared more reluctant to eat crickets. I would be curious to know if the type of prey fed to Belostoma affected their willingness or ability to breed.

    • I have not had very many flumineum as they are difficult to collect in any sort of decent numbers in my area, but I usually feed them mealworms when I do have them. I’ve never tried snails, but it doesn’t surprise me that they like them – most belostomatids do! I don’t know for sure whether different foods impact their wilingness/ability to breed, but I believe that it does. The females need a lot of protein and fats to produce eggs and the males typically don’t feed much (if at all) while they’re brooding, so both sexes have got to remain well fed to reproduce successfully. I’m sure some inverts are better sources of nutrients than others and that belostomatid foods would impact their reproduction. I know if I go away for a vacation or a conference and miss a week or two of feeding, my bugs (mostly Abedus) don’t produce as many eggs and are less inclined to mate than they normally are, though I’ve never done any research to confirm that my casual observations are actually correct. It’s one of those things I keep in the back of my head as a potential future experiment, though I’d certainly be happy to see someone else do it instead. To the best of my knowledge, it hadn’t been done yet.

          • Thanks! That is great! Your photos and description are very clear and helpful. I had checked your blog for info on sexing Belostomatidae, but missed that post. Last summer I spent a bunch of time going through various new and old manuscripts on Belostomatidae, and was surprised that I couldn’t find any with the information I needed.

            • I think that’s the kind of thing water bug people pass from person to person without ever actually writing it down. Hence the blog post! People ask me about it all the time so I thought I’d just make it available for everyone so I could stop writing the same thing over and over every time someone contacted me. Glad you found it useful!

  2. Hey, any tips on finding or catching these little guys? I spent 3 hours today looking in our local pond, in a variety of areas(since it’s quite large). I think I saw one, but it swam off to fast to identify it, but it seemed likely. I live in Sacramento, California if that’s any help.

    • They’ll be in the shallower water in vegetation along the edges of ponds if you’re looking for Belostoma or out in the open water somewhat further out if you’re trying for Lethocerus. My tip: be patient! It can be hard to find these guys, especially when they can spread out really far in the water.

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