The Carpenter Ant Family

2007 June 14

This time, we have several different individuals of a single species. First, in April, we started occasionally seeing worker ants in and around the house, like this one:


This is pretty clearly a black carpenter ant, Camponotus pennsylvanicus. As ants go, these are pretty big, about 8 mm long. It is possible to get them to bite, say, the edge of your fingernail, but they don’t so much hurt as just hang on. Anyway, after seeing these for a while, this next one showed up on the kitchen floor, so I refrigerated her for photography:



She’s not dead in that second picture, just stunned from being refrigerated [1]. This is a young queen, who either hadn’t mated yet, or who had mated but hadn’t yet torn off her own wings. The main distinguishing feature between her and the workers (aside from the wings) is that she’s easily twice as long and considerably more massive.

This next one was on our front window, and I didn’t recognize it as an ant at the time [2]:


This is a male carpenter ant. These are a bit longer than the workers, but thinner, enough so that they don’t even look like the same species, even without considering the wings. I think that I’ve been seeing these around for years, but never even realized that they were ants before.

Now, ideally, I should have gone to find a carpenter ant nest, cut it open, and pulled out some larvae and cocoons to make this little family portrait complete. Probably the easiest way to find the nest would be to just follow one of the workers home, but I haven’t done this yet. This might be a good idea in any case, because these ants build their nests by tunneling in decaying wood. They don’t eat the wood the way termites do (they are more of a symptom of damage to wood in a house, not a cause), but they do increase the area of damage and let the wood rot faster. If there is a part of, say, our house that is in bad enough shape that they are nesting in it, it would probably be good to know about it. As far as the photography of the larvae goes, all ant larvae and cocoons look about the same aside from the size, so maybe it would be easier just to dig up one of the ant hills in the back yard when I take pictures of the next ant species.

[1] She recovered completely. I let her go outside, where she might have mated and established a nest, but it is much more likely that something ate her, which is what happens to the vast majority of new queen ants.

[2] I thought it was some sort of wasp. An understandable mistake, since ants and wasps are reasonably closely related, and there are many, many species of solitary wasp.

10 Responses
  1. mark permalink
    March 9, 2009


  2. March 10, 2009

    Carpenter ants are large, and either black (like the ones on this page), or have a black head, red thorax, and black abdomen. I gather that “moisture ants” are smaller, and either red or brown. In either case, they really only burrow into rotting wood. Once wood starts to rot, they may bring in additional moisture to accelerate the rotting, but they are more of a symptom of a problem than the cause of a problem. If you remove the nest, replace the rotting wood, and keep moisture away so that the wood doesn’t start to rot again, they won’t be back. Good luck!

  3. Tony permalink
    June 11, 2009

    I’ve been delving in to the carpenter ants habitats, mating, how they live, and with who – there certainly doesn’t seem to be any breaking news about them out there – they are quite the creatures!

  4. lynn permalink
    August 16, 2009

    I found a nest above my dining room chandelier. I found larvae in creases in my dinging room chairs. I removed them. I consistently killed ants as they came out of the chandler and any where I could see them, including outside the dining room window. Today I don’t see them at all, either inside or out. Do you think they are gone?

  5. Roberto Granados permalink
    April 28, 2011

    You know,I was in Yosemite a few years ago,and there were these HUGE black ants(about 1″ long)all over the place.Some could fly,and some couldn’t.Do you have any idea what they might be?

  6. April 28, 2011

    Roberto: They were probably one of the other Camponotus species, related to the ones here. I expect you stumbled across a mating flight, with the winged ones being the unmated females and males. The unwinged ones would have been mated females (they tear off their own wings after they mate).

  7. Roberto Granados permalink
    May 3, 2011

    I had suspected that they were some kind of carpenter ant,but I wasn’t sure.They freaked out a lot of people staying at the lodge,and one woman actually screamed and fell out of her chair when one landed on her!

  8. Crystal permalink
    June 9, 2011

    I have these ants, i see them mostly at night and they like to sit in my sink mostly, with any dishes that might be there, but are also still seen there at night when no dishes are present…they mostly look like this pic u have on here, but no hair like stuff on the ‘butt’ and they are very dark and shiny black….are they carpentar ants? If so, or not, how the heck can I get rid of them? I have a one year old in the house as well as a 10 year old, he have bought little ant traps, (platic dome like houses with poison inside) but they dont seem to be doing crap 🙁 Please help me…

  9. June 10, 2011

    Crystal: If they look like this and are pretty good-sized ants, then yes, they are probably carpenter ants. As far as getting rid of them, the first thing I would do is try to locate their nest. You can usually do this by following one of them for a bit to see where it goes. Your 10-year-old might be willing to do this for you. In particular, if you were to put out a few drops of sugar syrup on a piece of cardboard where the ants will find it, after a while there should be a distinct line of ants from the sugar syrup to their nest that you can follow.

    Once you find the nest, you can see whether they are inside or outside. Sometimes a nest inside will be someplace where you can just vacuum them up and be done with it (we had one just lying on the floor under our refrigerator once). And if it is outside and they are coming in through an identifiable hole, you can just plug the hole. Otherwise, you can try placing your poisoned ant bait right next to the nest, to make sure they find it. The thing about ant baits is, they are not fast-acting, because the goal is to kill the queen in the nest. If a worker ant finds your bait, eats it, and then quickly dies then not much has been accomplished. But, if she takes a slow poison back to the nest, passes it around to her nestmates, and leads more of them to the bait so they take it home too, then the poison gradually builds up in all of the ants, including the queen. And then, even after the queen dies, it takes some days for the last few ant larvae to hatch out. So you might be looking at anywhere from two weeks to a month for poisoned ant-baits to completely eliminate a nest.

  10. Jo Anne permalink
    August 16, 2014

    I have these big black ants all over my back yard. They live in the ground. There is so many I can’t go out side in the yard. I’m not sure if they sting or bite. My little dog got into them and I had to take him to the vet. He almost died. he was biten or stung all over. Could someone please tell me what kind of ants they are? and how to get rid of them.

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