An Ant Mound Through the Year

This summer I spent a lot of time photographing some ants and their visitors around the nest of Allgeheny mound building ants, Formica exsectoides.  A lot about the ant is still a mystery to me, but I did learn a few things.

Here are a bunch of photos that show how the mound progressed throughout the season.

This is what the mound looked like on March 9, 2010.  The winter of 2010 was unusual in Iowa in that we had a very heavy show cover that lasted from the first part of December until middle March.  There were not the usual periods of freeze/thaw cycles which are usually hard on invertebrates.

At the base of the mound were some holes which I assume were made by rodents.  I don’t know if this is a normal or abnormal situation.

By April 11 grass was growing around the edge of the mound.  There was an area of thatch which did not seem to have grass growing at the top of the mound.

Here was the mound on May 15.

By June 16 the vegetation around the mound was getting pretty thick.  The mound is located in a patch of black walnut trees and there is a thick stand of giant ragweed around it.  I tried not to make any more changes to the vegetation than I absolutely had to, but I did remove some of the ragweed.

This photo was from July first.  I was not as good about regularly photographing the mound as I should have been, but I did not note any significant changes until October.

After a very wet summer and three or four weeks of dry weather a part of the mound seemed to have collapsed on October 8.  This may have just been a structural failure, or some larger animal may have caused it.

This photo taken October 9 shows more of the damage.

This is what the mound looks like today.  Any damage has been smoothed out, more likely by rain than by the ants.  It looks a lot like it did in March.


About the roused bear

Nature photographer from central Iowa.
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