INTRODUCTION.  These ants get their common name from their ability to inflict especially painful bites and stings.  The two most important species are the southern fire ant (Solenopsis xyloni McCook) and the red imported fire ant (Solenopsis invicta Buren).  The southers fire ant is a native species and ranges from California to southern South Carolina to northers Florida.  The red imported fire ant is from central Brazil and is found in the southeastern United States, from Virginia through Texas.

RECOGNITION.  Workers polymorphic, about 1/16-1/4" (1/6-6 mm) long; queens average 1/4" (6.6 mm) long.  Head and thorax yellowish red and abdomen black; reproductives darker.  antenna 10-segmented, with 2-segmented club.  Thorax lacks spines, profile unevenly rounded.  Pedicel 2-segmented.  Stinger extruded in most alcohol-collected specimens; readily inflict painful stings.
    Characteristics of the mandible and petiole (1st node of pedicel) will separate these 2 species.  The mandible of S. xyloni has 3 distinct teeth on its inner/biting surface whereas, those of S. invicta have 4 teeth and the petiole of S. xyloni has a ventral tooth near the node's attachment to the thorax whereas, S. invicta lacks such a tooth.

HABITS.  Fire ants are typically ground-nesting ants.  However, the southern fire ant will sometimes nest in the wood or masonry of buildings, especailly in areas near the soil or warmth such as fireplace hearths.  When the southern fire ant nests outside near a house, it is usually in the visinity of the kitchen.  OUtside nests are usually situated under stones or other covering objects, or in the soil at the base of a tree or shrub, or in clumps of grass.
    The red imported fire ant typically nests outside.  Each colony has its own territory, and there is usually no movement between colonies.  However, they will sometimes nest in areas of exposed soil within buildings such as bath traps.  They also have the habit of building outside nests adjacent to foundation walls.  They are commonly introduced into new areas via potted or balled shrubs and trees.
    Fire ants are attracted to electrical junction boxes of traffic signals, air conditioners, etc.  When they mass around the electrical contact points, they cause the equipment to malfunction.  They will also nest in gas and water meter boxes and then follow the pipes into the building.
    Fire ants prefer food with a high protein content but will feed on almost anything, plant or animal.  The southern fire ant has been known to remove insulation from phone and electrical wires and gnaw on clothing, especially if soiled.  They usually feed on seeds, insects, young tree bark, honeydew and other sweets, preferring oily meats and nuts.  Red iimported fire ants are particularly destructive to vegetation.  Workers forage in established trails.

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