Ant Crossing: April Theme Day

The Daily Photo first-of-the-month Theme Day for April is "yellow." I wanted to choses a photo that is expressive of Costa Rica, so I selected this "Ant Crossing" sign from the butterfly farm at Monteverde.
You can see ants crossing along the branch, including one ant carrying a leaf. Better photos of leaf cutter ants and their dirt mound are below.

Leaf cutter ants do not eat the leaves that they carry back to their nest. They feed the leaves to a fungus that they cultivate underground and the ants eat the fungus. I have a mental image of an underground blob that looks like Jobba the Hut being fed leaves, with ants gnawing around its edges.
Leaf cutter ants know what types of leaves the fungus likes, and what types of leaves are poisonous to the fungus. Sometimes in the forest there are so many leaf cutter ants carrying leaves that it looks like the ground is moving.

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