Avoidance of sticky mud by ants - - predator-free space?

Predators, like some species of ants, forage widely on many types substrates. We wondered whether muddy surfaces would be among them after learning that mosquito eggs often reside on sticky mud, leading to the hypothesis that ants avoid sticky mud (predator free space). We constructed a ninety-six cm diameter choice arena having eight wedges filled with organic soil hydrated at differing levels (pure water to oven dried). Twenty-five Harvester Ants, Pogonomyrmex barbatus, per run were released within a four cm diameter circle at the arena center. The positions of the ants were recorded intermittently over the next three hours. Ants foraged statistically evenly on soils varying from absolutely dry to seventy-two percent water. However, wetter soils registered eighty-four percent fewer visits supporting the hypothesis.