Temporal Changes in a Red Imported Fire Ant (Hymenoptera: Formicidae) Colony Classification System Following an Insecticidal Treatment

The decline of the red imported fire ant, Solenopsis invicta Buren (RIFA) following an application of fenoxycarb bait and the subsequent reinfestation from small, incipient colonies to large, mature colonies was studied in south Mississippi. Field colonies were rated using the numerical colony classification system of Lofgren and Williams (1982). The study site was considered RIFA free (98.9% decrease in pretreat population index) 3 months after a fenoxycarb bait treatment. Small incipient colonies categorized in class 7 (100–1,000 workers and worker brood present) appeared in the test site about 4 months after bait application. Mature colonies in classes 9 and 10 (10,000–50,000 workers present with worker brood and more than 50,000 workers with worker brood present, respectively) were detected after 12–15 months of development.