Ant behavior: January 2013 Archives

I am a typical mom who knows only three things about ants: they have structured colonies, they carry 3x their weight, and they invade our home during the rainy season. I had never noticed this behavior before and came upon your website in trying to research if what i think is happening is true. The black ants that I see in my bathroom are scouting for food and I don't kill them because I know they will not find any and will eventually leave, but some lone ants have become lost or stranded and I will see them roaming in the same area for a day or two and then they seem to die. Is it from starvation or cold temperature at night, or emotional distress at being alone with no way back to what they know as home?
Also, when they first invade there are many following a trail but soon I see that some break into groups of a dozen or so that scatter when they detect me, do they communicate in this way? I thought they were more like little robots following programmed instincts so they used chemical scent trails, but it almost looks to me like they are having a meeting to discuss their options. I use Clorox wipes to clean and have looked at the spot were they grouped to make sure there wasn't anything that could have served as food like my son's bubble gum toothpaste. I hope to learn more as I respect these tiny hard workers.

Thank you!
Claudia from central California

Hi Claudia,

Rather than thinking of ants as robots following programs, it might help understand what they are doing by imagining them as small people with a limited view of the world and very short-term memories. Contrary to popular belief, no single individual is in charge of an ant colony, not even the queen. Instead, an ant colony's behavior is accomplished through the independent action of each individual together. So every ant has to use the relatively small amount of information available in the immediate area to figure out what she should be doing. Oftentimes, this means "asking" other ants what they are doing and if they have an opinion on what everyone else should be doing. This type of communication is usually accomplished through antennal contact and scents and could certainly result in the formation of groups of ants all "talking" to each other, figuring out what they should all do next. Of course, it is always a possibility that they just found something interesting on the ground.

The ants that you find in your house are almost certainly looking for food. They could also be exploring for new nesting sites and, as your house is probably relatively warm, it might appear ideal at first. Unfortunately, no matter the reason for their exploration, foraging ants have very high rates of mortality around 15% per day. Many of these ants are the victims of predation or, in hot and dry areas, dehydration, but many simply get lost, as some of the ants in your house seem to. A scent trail may be too faint, may get disturbed, or the ants may get separated from it inadvertently and be unable to find their way home. Their eventual death is likely the result of starvation or dehydration although cold temperatures could certainly be a factor as well.

Deborah Gordon's book, Ants at Work is about how ants get all of their work done and it sounds like the subject might be of interest. You may want to check it out.

Thanks for your question,
Ben Rubin & the AntAsk Team

The other day I was sitting outside my house with my friend. He and I were just sitting on the ground. There were a number of small black ants around us going about their business but not really in our way. After some time they began to fixate around the area I was sitting. They climbed on my feet and gave little nips and so on. After a while it got a little ridiculous so I moved to the other side of my friend where there were no ants at all. It was completely clear and not in (what I thought to be) their trail. It wouldn't have been more than five minutes later and then they were back again. They were all around me and the spot I had been in previously was completely clear. I just couldn't figure out what it was about me??? I should point out that my friend was left alone the entire time. It occurred to me later however that it had been "that time of month" for me and was wondering if they were reacting to the change of hormone levels?

Thanks for any help you can give me

Dear CJ,

I have never heard of ants being attracted to human hormones before but without doing an experiment, it would be difficult to say for sure what was happening. Ants would be more likely to respond to food smells. Were you carrying any food or had you been cooking recently? A sweet smelling perfume could also be attractive to ants. However, smells and insect responses to them are often unpredictable. For example, certain termites recognize pen ink chemicals as trail pheromones and can be tricked into following ink lines.

Thanks for your question,
Ben Rubin & the AntAsk Team

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Dear Vidarshana,

This really is a great photo! Thanks for sending it to us! The darker ant in the center belongs to the genus Diacamma and the lighter ants surrounding and attacking it are members of the genus Oecophylla. The aggression between the ants may be the result of territoriality, predation, or a variety of other reasons.

Ben Rubin & the AntAsk Team

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