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Solenopsis invicta

Solenopsis invicta, commonly known as Red Imported Fire Ant (RIFA), is one of 266 species of ant in the genus Solenopsis. Solenopsis invicta belongs to the animalia kingdom, arthropoda phylum, insecta class, hymnoptera order, and formicidae family. They are originated from South America. It is believed that they are introduced to the U.S. through Alabama seaports as ship cargos.

Fire ants are symmetrical along the body, meaning that the left part is the mirror image to the right. The ants have hardened exoskeleton, meaning that they have no bones or internal supporting tissues, but tough integuments for support and protection. The fire ants breathe through their tracheas.

Their bodies can be classified into three major parts: head, chest and abdomen. They have three pairs of legs, and a pair of antennae attaching to the head. (personal interview) Just like other ants, the worker and soldiers ants are female. The queen is responsible for laying thousands of eggs. The number of males is low, because only one male is needed for the entire reproduction.

The life cycle starts with the queen mates with a male. After mating, the male dies, and the female begins to lay eggs. During the process, the queen has to survive on her previously deposited food and her shed wings as energy source. The queen would first lay about ten eggs that would also take ten days to hatch. It will be approximately twenty more days before the larvae become worker ants. As a result, the first worker ants are very small in size. Gradually, the size and the number of worker increase as the queen is fed with more nutrients.

Unlike most peopleís perception that fire ants bite and inject venoms, they actually have stings like most wasps and bees do. The stings are located at the end of their abdomens. When the fire ants sting, they use their strong mandibles to attach themselves to the victimís flesh, and then they can sting for many times continuously.

Since the 1940's, after their initial arrival, they have increased exponentially in numbers, doing more harm than good. They build mounds, no larger than 46 cm. in diameter and 18 inches in height, on soil close to homes and other buildings, sometimes forage indoors for food and moisture. They are a nuisance and can threaten sleeping or bed-ridden individuals and pets. Occasionally, they feed on vegetable plants in home gardens. The worst damage usually occurs during hot, dry weather; they invade flowerbeds seeking warmth and moisture. If disturbed, they bite and sting the intruder. The sting of the RIFA has venom composed of a necrotizing alkaloid which causes both pain and white pustules that appear one day after the sting.

These ants have received more attention because of the damage they have caused to farmers, buildings, and even physical damage to animals including humans. They are extremely aggressive and has the ability to deliver venom in unisom.

They are attracted to electrical fields and crawl into air conditioning units and the wiring of stop-lights until they short them out. This is the leadiung cause of traffic light shorts in Texas. It should be noted that they are excellent natural predators, biological controls, for pests such as the sugarcane borer, the rice stink bug, the striped earwig, aphids, the boll weevil, the sybean looper, the cotton leafworm, the hornfly, and many other pests harmful to crops. Seeds, fruits, leaves, roots, bark, nectar, sap, fungi, and carrion are all on their menu, they are not shy about creating their own carrion either. They are proficient enough at overwhelming intruders that they can pretty much clear an area of invertebrates, lizards and ground-dwelling birds.

The red fire ants are foreign, they have virtually no natural enemies in the States. Fortunatly, many scientists and agencies are developing prolific methods to stop the spread of fire ants.

The prevention of plague has been through pesticide use, but current research is introducing natural enemies of the red imported fire ant -- microsporidian protozoan Thelohania solenopsae and the fungus Beauveria bassiana are promising pathogens. Pseudacteon tricuspis and Pseudacteon curvatus, parasitoid flies from South America, decapitate worker ants in the final stages of larval development. Solenopsis daguerri (Santschi), a parasitic ant, invades RIFA colonies to replace the queen in hopes of gaining control of the colony. For this reason, it is also being probed as a biological control agent.