My Wife and I bought my Son an ant farm for his birthday and we're enjoying watching the everyday interactions of the ants. We followed the instructions in the guidebook that came with the ant farm and caught approximately 20 ants in our back yard and introduced them to the colony. I believe they are 'pavement ants' (they're fairly small and light brown in color). I also think they are all workers as there is no noticeably larger ant that could really be considered to be a queen.
There are a few questions we'd like to ask.
1. Will our ants ever reproduce? According to the guidebook, sometimes workers without a queen will start producing their own offspring. This doesn't appear to be happening in this case as the number of ants is dwindling. We started with around 20, but now there only seem to be 6 or 7 or so left. (It has also been about 3 weeks now, and according to what I've read on the internet, pavement ants tend to have a lifespan of 3 to 4 weeks, so this is probably natural).. However, I've also read that in most cases the offspring produced (if any) would be male, which wouldn't be any use to sustaining the colony in an ant-farm context.
2. If they die out, can/should I introduce other ants? Presuming that the probable outcome will be that the ants will die of old age without reproducing, we would like to repopulate the colony. However, I'm concerned that this might be unfair to the new ants, as they might be forever on their guard due to the old ants' pheromones being everywhere. Would this be an issue?
3. What would be a good (locally available) sort of ant to introduce? We're in Manitoba, Canada. I've only seen two species of ant around here (that I can distinguish) - one is the pavement ants, the other is a sort of shiny black ant about 3 times bigger than the pavement ants and seems a lot more aggressive. When I was catching the pavement ants, one of these wandered by and they all got out of its way. I also watched one of the black ants have a furious struggle with a caterpillar and drag it off somewhere. I'm thinking these would be fun to observe, but I also don't want to cultivate something that swarms all over me when I open the food and water holes on the farm. (The pavement ants tend to run away.)
4. Is it 'right' to capture a queen? It would probably be in our best interests to get hold of a queen in order to keep the colony going. However, I don't want to destroy an existing nest in order to get one. Conversely, I don't really want to have to keep 're-booting' the colony every couple of months. What would be a viable (and ethical) way to get hold of a queen?
5. Can/will they overpopulate? The alternative worry to having too few ants is having too many! Do they regulate their population growth according to the space they have or do they just keep reproducing? I'm assuming that in the wild they would just expand their living space to deal with the new population, but in the context of an ant-farm environment, they could get a little squashed. Is this an issue?
Thanks for your help,
Steve - Winnipeg, Manitoba.
Great to hear that you are enjoying an ant farm! Here are the answers to your questions:
1. The guidebook is correct in that workers are usually sterile. In rare cases they can start laying unfertilized eggs that will develop into males. Ants (and honey bees) have a so-called "haplodiploid sex-determination system". Fertilized eggs are diploid and will develop into females, while unfertilized eggs will develop into males. Queens usually go on a mating flight, and become inseminated, and this gives them the chance to lay fertilized eggs that will develop into females. Workers, on the other hand, will never mate. In the absence of a queen, they might develop unfertilized eggs, which develop into males. However, I think it is unlikely that this will happen in an ant farm.
2. I would not be too concerned about the pheromones. Just introduce new ants to the ant farm once all the other ants have died. If there are still a few ants left, you could take them out, put them in a little plastic container and freeze them over night. That is an easy way to kill them. Only if the farm gets too messy, I would exchange the substrate.
3. For your third question, I contacted another ant expert, James Trager, and here is what he had to say: "Though some Myrmica species there may sting with perceptible effect, they are smallish and not very likely to sting. There are no large stinging ants in Manitoba. The larger ones the writer mentions are probably a Formica species, which are effective predators, even though they completely lack a sting. Some Formica are rather aggressive and may bite when their nests are invaded, they nevertheless can make rather good captive ant colonies. I must qualify this by mentioning that in general, the bicolored (red and black) species do not thrive in captivity, but the all black ones do. On the other hand, pavement ants (Tetramorium), though smaller and pretty good escape artists (as the writer notes), also make good captive colonies, if properly cared for in a well-sealed apparatus."
4. I would not dig up an ant mount, but if there are some pavement ants and you are not destroying the landscape, I'd say go for it! However, the best way to get hold of a queen would be to capture on right after it's mating flight. The queens will still carry wings, but after they have mated, they will take them off and try to dig into the soil. This would be the perfect time to introduce her into a ant farm. The survival rate of mated queens is not very high, so if you have the chance to find several, I would keep them in little plastic containers with a bit of dirt first. If there is one that starts producing workers, I would take that one with the newly emerged workers and introduce her into the ant farm.
James Trager has some useful advice on how and when to obtain a mated queen for your ant farm: "In fact, there are plenty of mating flights yet to happen across North America (and especially that far north, including some as late as mid-September). These occur in the big genera Formica (now through mid-August), and Lasius & Myrmica (now into September, depending on species). Also, some species may readily be collected as entire colonies under stones on wooded slopes, though, whole colonies can be difficult to handle and their queens difficult to get without some good basic equipment and experience."
5. I would not worry about having too many workers in your ant farm. If you had the luck of obtaining a reproducing queen and had too many workers, you can always take some out and freeze them. Read this post on the best density of workers in an ant farm.
Good luck with your ant farm!
James Trager (guest expert), Steffi Kautz & the AntAsk Team