Dear Ant Blog,
We have an in-ground pool with a concrete deck. Over the years, cracks have appeared as expected from expansion and contraction. Unexpectedly, ants have started coming in through these cracks. At one crack, there is a swarm of little black/dark brown ants who come out, sometimes holding little white objects, and throw themselves into the water. There they form into large clumps, about the size of a Ping-Pong ball, and float around. We have also noticed larger ants that we think are guard ants. We tried to take photos, but the camera kept focusing on the bottom of the pool instead of on the ants. One theory we had was that this might be a way of starting a new colony. Just float off with some eggs and guards and start up where you land. Also, when we scooped one clump out with the skimmer, it promptly dispersed and the ants began swarming towards the hand holding it. This hasn't happened before, and we have been here for several years. Do you have any explanation?
Thanks for your interesting question and observation. We have deferred to colleague that happens to have quite a lot of experience with ants in the Gainesville area and with Solenopsis invicta, the Red Imported Fire Ant (which is what you are finding in your pool). Here is what Lloyd Davis had to say:
"The ants appear to be the Red Imported Fire Ant, Solenopsis invicta. This species was introduced into the Southeastern US sometime between 1930 and 1950. It came from South America, probably near Argentina or Brazil. In its native habitat, the area surrounding a nest may be subject to unpredictable flooding. These ants will cling to one another when flooded out of the nest or if they are trailing and fall into water. I can't tell you why they ended up in your pool. It is possible they were attempting to get to some other kind of insect that had also fallen into the pool."
In addition there is a great video about this behavior of fire ants from the BBC, which can be watched here.
Thank you for contacting us,
Lloyd Davis (guest expert), Corrie Moreau & the AntAsk Team