This is another photo of the trails through the grass at the Intel plant in San Jose made by leaf cutter ants. This shows one of the burrows, and the trail leading away from it.
The leaf cutter ants bring back leaves, of course, not grass. So why would they chew the grass to cut it down to the dirt?
My presumption is that they are making it a lot easier for themselves to walk back to their den along the bare ground rather than having to climb through the stalks of grass. It would be particularly strenuous to walk through the gras carrying large leaves on their backs.
This is similar to building a paved road. They are pretty smart for having only an ant-sized brain.
This week we are showing photos of Dublin, Ireland, on our Viva la Voyage travel photo site.