Fire ants frequently invade home lawns, school yards, athletic fields, golf courses, parks and other recreational areas. Additionally, electrical equipment and utility housing, home gardens, compost piles, mulched flowerbeds, pavement cracks, and the perimeter of bodies of water must all be considered when choosing a method of control.
The human toll from RIFA stings is an important public health concern. Stings may produce a large range of reactions from localized pain and swelling to anaphylactic shock, making it hard to estimate the cost to public health.
Red Imported Fire Ants (RIFA) & Other House Nesting Ants
Two species of fire ants are found in Florida. Most notorious is Solenopsis invicta , the red imported fire ant (RIFA), followed by the much less common Solenopsis geminata (Fabricius), the tropical or native fire ant. Other more common U.S. members of this genus include Solenopsis xyloni, the southern fire ant; Solenopsis aurea , found in western states; and Solenopsis richteri , the black imported fire ant, confined to northeastern Mississippi and northwestern Alabama. RIFA is native to central South America. It is also established in the U.S. and Australia.
Alates (Swarming Ants)
Mating flights are the primary means of colony propagation, secondarily, budding can occur in which a portion of a colony becomes an autonomous unit. After the colony reaches one year of age, reproductive alates are produced. Six to eight mating flights consisting of up to 4,500 alates each occur between the spring and fall . Mating flights usually occur midday on a warm (>74°F/24°C), sunny day following rain. Mating occurs during flight and the males die soon after mating with females. In the southern United States, as many as 97,000 queens may be produced per acre of infested land per year. Alates are often attracted to swimming pools where homeowners can find thousands of winged ants trapped on the water’s surface.
After mating flights occur, it is common to find newly-mated queens clustered together under shelter. This clustering and the cooperation of the newly-mated queens aid in establishing a colony. However, as the colony grows all but one queen will be killed, except in the instance of multiple queen colonies.
Once the female alate has mated, she will rake her legs forward to snap her wings off at the basal suture and find a suitable spot to begin a new colony. Often this spot is under rocks, leaves or in a small crack or crevice, such as at the edge of a sidewalk, driveway, or street. The queen will burrow into the soil to excavate a small chamber, which is sealed off to keep predators out. Within 24 hours of mating, the queen will have laid between 10 to 15 eggs, which will hatch in eight to 10 days. By the time the first group of eggs hatch, the queen will have laid from 75 to 125 more eggs. The larval stage typically lasts six to 12 days and the pupal stage for nine to 16 days. The newly-mated queen will stop laying eggs until the first batch of workers mature. This process takes from two weeks to one month. The queen will feed the first batch of young larvae oils regurgitated from her crop, trophic eggs or secretions from her salivary glands. The queen’s wing muscles, which are no longer needed, break down to provide the nutrients for the young larvae.
The first workers to emerge are characteristically small due to the limitations in nutrients that the queen provides. These workers, termed “minims,” burrow out of the chamber and begin foraging for food to feed the queen and new larvae. The minims also begin construction of the mound. Within one month, larger workers are being produced and the mound is growing in size. By six months the colony has reached several thousand workers and the mound can be seen in a field or lawn. Colonies of this size generally contain a few large workers (major workers), many medium sized workers (median workers), and a majority of small workers (minor workers). The three types of workers are all sterile females and serve to perform tasks necessary to maintain the colony. The queen is the single producer of eggs and is capable of producing as many as 1,500 eggs per day. Mature RIFA colonies may contain as many as 240,000 workers with a typical colony consisting of 80,000 workers.
The diet of foraging workers consists of dead animals, including insects, earthworms, and vertebrates. Workers also collect honeydew and will forage for sweets, proteins, and fats in homes. They are sometimes attracted to piles of dirty laundry. Larvae are fed only a liquid diet until they reach the third instar. When the larvae reach the fourth instar, they are able to digest solid foods. Worker ants will bring solid food rich in protein and deposit it in a depression in front of the mouth of the larvae. The larvae will secrete digestive enzymes that break down the solid food and regurgitate it back to worker ants. The queen is fed some of the digested protein to support egg production. As long as food is plentiful, egg production is at its maximum.
Five Common Types of Ants
There are thousands of different pests that can plague a home, but ants remain one of the most common in the United States. Here are a few of the more common squatters.
Carpenter Ants: One of the largest ant species, these red or black pests can be found throughout the US, most commonly in the north. Their name comes from the way they excavate wood to build their nests. Though they don’t eat the wood like termites do—just deposit the debris outside their nest—the tunnels they bore can weaken the structural integrity of a home over time.
Odorous Ants: These are small dark brown or black ants that, when smashed, give off a smell akin to rotten coconut. Foraging night and day, this species moves its nest regularly according to rain conditions. Inside, they live near moisture sources, such as in wall cavities near hot-water pipes or beneath leaky fixtures and water-gun cabinets.
Acrobat Ants: So named because of their tendency to raise their head over their abdomen when threatened, these ants often nest in areas already cleared out by termites or carpenter ants. They can pose a risk to homes since they sometimes strip the insulation from electrical or telephone wires.
Argentine Ants: Dark brown to black in color, these ants are often found in the southeast. Wherever they build their nests—under boards or stones, beneath plants, or alongside sidewalks—their well-defined foraging trails serve as a telltale sign of infestation.
Fire Ants: Since it first appeared in the US in the 1930s, the fire ant has plagued humans and animals alike with its painful bites and stings. Found throughout the south, fire ants favor warm, sunny conditions, so they actually tend to avoid shaded areas when building their large, irregularly shaped mounds.