Identificaciones de scottmcneir

Using iNat's suggestion. I measure these ants to be about 5 mm in length.

This was the most amazing ant trail I have ever seen. It went between several oak trees and was about 160' (48m) in length. I estimated the density with a tape measure of about 187 ants / meter, resulting in about 9000 ants on the trail. The trail also was darker than the adjacent dirt due in part to what may be a the roots of grass which have been leveled. These darkened "roots" are shown in the last photo. Maybe the roots are soiled from the ants continually walking over them?

The nests appeared to be at the base of the trees, however, ants were also climbing the trees. At other sites we saw ants entering knot holes and cracks in the trees.

The tree is shown in a subsequent observation:
https://www.inaturalist.org/observations/231454415