Factors that induce emergence and flight of southern fire ant alates (Hymenoptera: Formicidae)

Alates of southern fire ant, Solenopsis xyloni (McCook), emerged 2 h before sunset from May to October in southern California. Emergence appeared to be associated with the time of day and light intensity. Other abiotic factors that may also influence alate flights include rainfall, relative humidity > 60%, and wind speed < 8 km/h. Spraying alates with paint provided an effective, long-lasting marking technique that did not affect survivorship. Marked alates survived up to 15 weeks in the laboratory and field. Swarming at an inland site occurred in June, July and August. When swarming did not occur, alates returned to the colony within 15 min of sunset. The lack of swarming at a coastal site in San Diego was attributed to continuous sea breezes in excess of 8 km/h.