Pavement Ants Love Fritos! And Have Big Nests!

2013 January 19

Back on March 23, 2012, I found this Frito corn chip on the floor at work, covered with a few dozen pavement ants. This was in about the same place as I had previously found an ant-covered snack chip, and the ants probably came from either the same nest or a daughter nest[1]. They are most likely the Immigrant Pavement Ants, Tetramorium immigrans

They evidently like the oils. The chip looked dried out and porous, as if they had excavated out all of the oil-rich regions.

I’m getting a little better at photographing ants, so these pictures of individuals are slightly more clear than last time. They are still hard, though: ants really hate to hold still.

One way to get them to hold still for a moment is to get them to make a threat display at the camera:

They can’t hurt a person much, but they sure do try. When you open up a nest of pavement ants, they swarm up your arms and bite as much as they can, and it feels like being lightly poked with hundreds of tiny pins. They also seem to try to pull out your body hairs. It doesn’t so much hurt, as itch like crazy.

And how do I know what they do when you open up one of their nests? Because I opened up this one, that we found under a paving stone in our yard on June 23, 2012:

This only shows a small portion of the entire huge nest. There must have been tens of thousands of them under that stone, swarming everywhere. And there were tunnels leading down, so the nest must have extended well below the stone proper.

You may note that the grubs the ants were tending were a lot bigger than the ants themselves. This is because those grubs were going to grow up to be potential queens, which would fly off, mate, and mostly get eaten by predators. But a few would establish new nests[2]. At any rate, those big grubs were very convenient for feeding to the ant lion we were rearing at the time. The grubs were about the size of a grain of rice, and if we had wanted to, we could have probably harvested a cup or so of them. I’m told that ant grubs are pretty tasty when fried up with rice, by the way. And if you use brown rice, your victims dinner guests may not even realize what they are eating until you tell them.

[1] Shortly after I took the March pictures, I noticed that the building custodians had put out some ant-baits. I haven’t seen any of the pavement ants around that area since, so the nest has probably been killed off. I suppose I could drop another chip there sometime, just to be sure . . .

[2] Once an ant nest gets established, it can last a long time[3] and emit thousands of potential queens. So their success rate in establishing new nests doesn’t have to be very high for the species to be successful.

[3] Browsing around, I see pretty frequent notes that pavement ant nests often have multiple queens, which would certainly account for both the size and the longevity of the colonies. The only question in my mind is, how does the multiple queens thing work? Do some of the queens fly out, mate, and then come back home to live with Mom? Do groups of sisters band together after mating to form a colony together? Do new queens find existing nests of relatives, and set themselves up on the outskirts so that their colonies can gradually merge? Or do they manage it some other way?

4 Responses
  1. January 20, 2013

    Semi-off topic: Here in San Diego, it never gets cold enough to slow down the termites, so we’re always under attack. While talking with pest control guy who was tenting my house, I learned that termites are like a long-range shotgun attack. Almost none of the mated queens ever get anywhere, it’s just sheer numbers that has one find an opening into your house. Most fly all over the place and never find a way in to a potential nest. That made the preventative goal: close off all termite-sized holes in your wood with plenty of paint.

  2. January 21, 2013

    It is interesting the different ways that colonial insects establish new colonies. The whole “shotgun” approach seems fairly common, but has a pretty pathetic success rate. I’ve tried catching the new ant queens on several occasions to see if I could get them to establish a new nest, but I have yet to get the conditions right and they never succeed. They must only manage a new nest if they are phenomenally lucky, and find a nest site that is *just so*. The success rate of ants and termites that reproduce like this looks to be only be a tiny fraction of a percent.

    The ones with the highest success rate seem to be the ones like honeybees, where the colony raises up a new queen, and then splits, with a bunch of workers going off with one queen to establish a new colony while the rest stay put with the other queen. They end up investing a lot more in each new colony, but the odds of success go way, way up, often better than 50%. They’re approaching reproduction much more like mammals do, with a big investment in their offspring, and not much like the scatter-shot approach most other insects use.

  3. January 21, 2013

    The story about your “pet” ant queens instantly made me wonder if there wasn’t more to it. You need the right place and the right ant. It may be that not all mated queens can manage to start a new nest even under perfect conditions.

  4. January 21, 2013

    Yeah, I wondered about that too. I try to only collect queens that have shed their wings, and therefore presumably mated, but who knows whether they actually mated successfully or not? Or whether they are even fertile?

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