Pecan,Carya illinoensis(Wangenh.) K. Koch, orchards provide an important habitat for the red imported fire ant,Solenopsis invictaBuren, and orchards from middle to southern Georgia were heavily infested. Honeydew produced by blackmargined aphids,Monellia caryella(Fitch), on pecans was an important source of carbohydrate food forS. invicta, which were found foraging at 9-m heights in trees. Mowing of orchard ground cover caused a change in the ratio ofS. invictaon the ground to that in trees but was not correlated with outbreaks ofM. caryellain trees.S. invictawas a major predator of eggs, larvae, and pupae of a green lacewing,Chrysoperla rufilabris(Burmeister), and of the pupae ofAllograpta obliqua(Say) in pecans but had little effect on the eggs ofHippodamia convergensGuérin-Méneville. A close mutualistic relationship betweenS. invictaand the mealybugDysmicoccus morrisoni(Hollinger) was discovered.S. invictapromoted the development of colonies ofD. morrisonion callus tissue located on the main stem of trees by covering the colony with soil and debris, by defending the colony, and by collecting honeydew.