Friday, April 13, 2012

Ant Mound Attacked

Seen from a distance, the mound of an Allegheny Mound Ant, Formica exsectoides, should display a fairly uniform curve.  When it has a shape such as this, you know there’s been a problem.

Some animal took out a 20 inch wide section clear across the mound.  There must be something awfully tasty in there for something to invest this much effort in excavation work.  This has got to be the work of a larger mammal, but it’s hard to imagine the reward being sufficient for this type of exercise.  In the warmth of the afternoon sun, the ants were enthusiastically attacking me as I knelt beside the mound.  I wasn’t concerned because the ants were only biting my clothing.  The intruder probably took the brunt of any colony defense with his hair and didn’t care anymore than I did that he was covered with ants.

It’s hard to tell how long ago the attack occurred.  Undisturbed soil on the surrounding leaves show that it hasn’t rained since the time of excavation, but it hasn’t rained a drop in two weeks, so that doesn’t narrow it down much.  Plants uprooted from the top of the mound were well desiccated, indicating that their roots have been exposed for several days.

There was quite a path of destruction left by the attack.  It looked like at least 8 inches had been removed from the top of the mound.

The mound material is full of tiny limestone crumbs that come from the pulverized bedrock beneath the soil.  Soil depth on this site is just over half a foot, so I’m assuming the presence of the limestone means that the colony has built its tunnels and chambers down into the bedrock.

The ants are busy making repairs, but the mound really needs some water to help things along.  The soil is just dust and rocks that won’t stick or stack.  It’s like trying to make sand castles with dry sand.

It may be well into summer before the mound is back in shape. Some ants will continue with the repairs while others forage for food and perform other colony duties.  Maybe I should pitch them a treat from time to time, so some of the food gatherers can stay at home and help with the building.


  1. Hi James. Bears sometimes wander through this part of Ohio, but we don't have any residents near here. It would certainly be exciting to find a bear digging up an ant mound, but I doubt that will happen any time soon.