Tetramorium caespitum

The Pavement Ant

Lots of plants and animals change their behaviour in response to changing environmental conditions, and ant colonies are no different. The Pavement Ant (Tetramorium caespitum) nests in sidewalks or under paving stones, boards and other disturbed habitats with dry, well-aerated soils. This same little ant (3mm) can be a household pest as it forages on a variety of kitchen crumbs and leftovers.

Last week when the temperature was seriously warm, I came across several swarms of ants boiling out of cracks in the pavement. My kids and I noticed them right away on our walk to the bus stop and were immediately fascinated by what on earth they might be doing. It turns out that the swarming behaviour is analogous to a moving party. When the colony gets too big or cannot be supported by the environment, it splits off with a new queen to form an entirely new colony elsewhere. If you watch closely you will see them not simply swarming, but trailing off in a certain direction to find a new abode.

However, as we can all attest to, moving parties aren’t always fun. As colonies attempt to conquer new areas, they will often attack nearby enemy colonies – there’s only so much real estate in the neighbourhood. Attacks can result in huge sidewalk battles, sometimes leaving thousands of ant carcasses behind.

Next time you’re walking down the street and see an ant swarm, take a few moments to glimpse into a whole other world – you might be fascinated by what you see.