he brood chamber and begin to forage for available food. Soon another generation of larger adult workers has developed and the colony begins to grow. Workers start to emerge daily and within 6 months the colony population approaches several thousand and an above ground mound is visible. The polymorphic (poly in Latin means many and morph means form) nature of the worker becomes more apparent. The largest workers in the colony (majors) can be as much as 10 times the size of the smallest workers (media). The queen lives up to 7 years and produces an average of 1600 eggs per day. At maturity, a monogynous (one queen) fire ant colony can consist of over 250,000 ants. As discussed above some fire ant colonies have only one queen per nest while others can have many queens and are called polygynous colonies. The polygynous colony may be more difficult to control because all the queens must be killed to prevent the colony from surviving. Polygynous colonies frequently expand by "budding"; i.e., some of the queens and workers break off from the parent colony and start a new mound nearby. This process in polygynous colonies can accounts for much higher mound density which sometimes approaching 1,000 mounds per acre.
Different sized worker adults. Image courtesy of USDA Archives.
One of the identifying characteristics of an imported red fire ant colony is the earthen nest or mound. This mound is a cone-shaped dome with a hard crust. They averages 1 ½ feet in diameter and 8-inches in height. In heavy clay soils they can exceed 3-feet in height and 4 1/2 feet diameter. There are usually no external openings in the mound; but tunnels a few inches below the surface tunnels radiate several feet from the mound allowing foraging workers access to the colony. These mounds serves several functions: They act as a flight platform for nuptial flights and to raise the colony above ground in excessively wet soil while protecting it above ground from intruders and rain. They also serve as a passive solar collector to supply warmth to the 