The external nest structure of Pogonomyrmex bicolor
can take many forms, including small craters made of sand and pebbles, large low sandy mounds up to 0.9 m / 3 ft in diameter, or even indistinct entrance holes with little superstructure. This image shows the larger of two P. bicolor
nests at this location - we were shocked to discover that this substantial crater was made entirely of chaff
! There was no significant sand or gravel structure below this discarded plant material. This nest was in the middle of a foot path, and bears a human footprint on its southern rim. Unpainted portion of measuring stick is 1 foot in length - red indicator points north.