The swarming and mating of harvester ants was observed in Utah in July 1979. Workers groom the alate forms outside the mound before swarming occurs and are highly aggressive in protecting them. Mating pairs apparently are not disturbed by other ants. Fertile females likely use moving vehicles that extend their dispersal.
Allred, Dorald M.
"Swarming of the western harvester ant, Pogonomyrmex occidentalis,"
Great Basin Naturalist: Vol. 40
, Article 13.
Available at: http://scholarsarchive.byu.edu/gbn/vol40/iss2/13