We headed south the first part of February, to Texas and then to Costa Rica.  While in Texas we visited two of my favorite places: Attwater Prairie Chicken National Wildlife Refuge and Brazos Bend State Park.  If you want to see alligators (and birds) go to Brazos Bend, but if you want to see leaf-cutter ants (and birds) go to Attwater. 

One of nature's marvels (as well as delightful entertainments) is the site of leaf-cutter ants. They are fascinating and totally mesmerizing to watch. When you come upon a leaf-cutter "highway" you are witness to creatures participating in one of the largest and most complex animal societies on earth—second only to humans.  We had good looks at leaf-cutters in Texas:

When we were in San Luis, Costa Rica, staying at the University of Georgia Campus, we saw much larger "highways" and learned a lot about leaf-cutters. I always thought they ate the plants they cut. But that isn't so. The plant parts are too poisonous for them to eat.  Instead, the parts they gather are used to grow a unique species of fungus which is the ants' only source of food. This fungus is essential for their survival; and they are the only ones who know how to grow it.

The tasks in the colony are divided among different specialized groups of ants.  All jobs are essential; and, aside from the queen, no one is more important than the other.  Large, younger ants cut and transport plant fragments to the colony:

Inside, workers chew the plant material which becomes the substrate for the developing fungus. The queen lays her eggs in the fungus and the larvae that hatch feed on it so they may grow into adult ants who will continue to carry on the responsibilities of maintaining their vast and complex society.

Defense of the colony is carried out by large soldier ants. They are bigger than the cutters, and have impressively large mandibles. You can see one here defending the entrance:

Another important task is keeping the inside of the colony clean. This job is fulfilled by smaller and, I have read, older ants.  Here are some workers carrying dirt or detritus away from the colony:

While in Costa Rica we were shown several enormous ant colonies:  one that took up the whole side of a hill and was estimated to be inhabited by 8 million or more ants.  We also saw several tree trunks supporting vertical ant highways. It was very cool to watch, at eye-height, these tiny industrious creatures traveling in straight, disciplined lines up and down the trunk of a tree:

For more in-depth information about leaf-cutter ants try these websites:  https://microbewiki.kenyon.edu/index.php/Leafcutter_ants,_fungi,_and_bacteria#Symbiotic_Processes  and   http://currielab.wisc.edu/video_gallery.html

You might like this short video: http://www.youtube.com/watch?v=6qKySmzGgwo  And here’s a link to a live Antcam where you will see ants all over the white fungus as they tend to it. You should also see some ants moving and chomping on pieces of plant material:  http://currielab.wisc.edu/antcam/