The effect of thatching ants (Formica obscuripes) on number of spiders found on sagebrush (Artemisia tridentata) was determined by comparing spider abundance on shrubs at different distances from ant mounds. Spider abundance was inversely related to proximity to mounds. Spider abundance on shrubs abound abandoned mounds revealed no effects of mound proximity. Two mounds in which ants were exterminated showed a declining effect of mound proximity 1 month after treatment. One year after treatment there was no effect.
Heikkinen, Michael W.
"Negative effects of the western thatching ant (Formica obscuripes) on spiders (Araneae) inhabiting big sagebrush (Artemisia tridentata),"
Great Basin Naturalist: Vol. 59
, Article 11.
Available at: http://scholarsarchive.byu.edu/gbn/vol59/iss4/11