Origin: Thought to have arrived from Brazil in ship transporting coffee around 1891, and now found throughout North America, in Hawaii, and on most other continents throughout the world.
Biology: Though the Argentine Ant is a small, non-stinging ant, it is a very territorial and aggressive ant that will drive away or kill competing ant species. Neighboring colonies of Argentine ants appear not to be aggressive toward each other, allowing for the rapid spread and domination by this species. Colonies contain thousands of workers and many queens, and mating will take place within the confines of the colony. New colonies are often formed by budding off from the parent colony. Nesting is usually in the soil, commonly under concrete slabs, but may also be found in any other convenient void, such as in trees, wall voids, or under debris on the soil. Soil nest are generally very shallow. While protein foods are part of their diet, their preferred foods are sugars, including household food products, fruits in gardens.
Odorous House Ant
Origin: Native to North America, and found throughout much of southern Canada, all of the U.S., and into Mexico.
Biology: The house ant can easily be confused with the Argentine Ant, but is a shinier black color. The name is derived from the strong odor given off when the ants are crushed, said to resemble rotting coconuts. Workers are all the same size and forage in long, distinct trails. Colonies may have up to 10,000 workers in them, and nestling sites may be almost anywhere. Outdoors they make shallow soil nests under any material on the ground, within hollow trees, or in any other cavity available. Indoors they nest in wall voids, under insulation in crawl spaces, or within cavities in the wood. Sweet materials like honeydew or other sugar sources are their preferred foods.
Origin: Fire ants originated in South America, entered the United States in the southern states around 1930, and spread rapidly to 17 southern states. It has since spread to California and isolated incidents have occurred in other states.
Biology: This is one of the worst ant pests in the U.S. in terms of human health, property damage, and environmental damage. Colonies may have several hundred thousand workers and dozens of queens in them, and workers very aggressively defend their nest with stinging. Their nests may be located in equipment, causing damage to it, as well as within structures. Nests most commonly are in the soil, identified by the large mound of soil raised above the surface, and they are particularly common in turf. The workers are aggressive predators, feeding on any other insects they find as well as small mammals or birds, earthworms, frogs and lizards. They dramatically alter the natural habitat when they move into an area. Fire ant nests may go as deep as 8 feet in the soil, and have mounds above ground as tall as 3 feet and 2 feet in diameter. They are nocturnal except when the mound is disturbed, at which point they rapidly overwhelm the intruder, and on a chemical command commence stinging simultaneously. There may be numerous queens in a colony with numerous satellite colonies attached.
Control: Due to the large colony size, deep nests, and sensitivity to chemicals, baiting is a preferred method of control, and baits with an oil attractant appear most acceptable. Physical disturbance and flooding of the mounds do not work. Elimination of unnecessary moisture sources will reduce the attraction of an area for these ants.
Origin: Numerous species of these ants native to North America, particularly in the drier, warmer regions of the United States and south into Mexico. There are more than two dozen species known, with only a single species found east of the Mississippi River.
Biology: Harvester ants gather seeds and vegetation for their food, and are very unlikely to enter structures. However their activities can have a serious effect on agricultural crops or ornamental plantings. The black harvester ants apparently do not sting. Nest openings are identified by the large, circular, flat area around them, created by the workers as they clear debris and soil from the underground chambers. This area averages 12 feet in diameter, and paths lead from it to over 200 feet away for foraging. Nests may go as deep as 15 feet, with numerous chambers, and the population of workers may exceed 12,000. Swarming by reproductives occurs throughout the summer months.
Control: Harvester ants are not known to forage or nest within structures, although their nests may be under slabs or porches around the exterior, and commonly in lawns and other urban areas.
Treatment: Treatment would be directly into the nest with a residual dust insecticide or granular baits which would be placed near nest entrances.
Little Black Ant
Origin: Possibly a native of the United States, where it is found most commonly in the eastern half, but frequently in California as well.
Biology: When found outdoors this ant nests primarily in the soil under debris or other objects, as well as in open areas and in turf. The nest opening will have a small crater of soil around it. This ant is one of our smallest, with workers only about l.5 mm long. Colonies are small but have numerous queens, and will relocate when they are disturbed. Preferred foods seem to be sugar materials, but they also feed on protein from live or dead insects.
Control: Control of most ants includes correction of the attractions that drew them to a property, including harborage sites, food sources, and moisture conditions. Elimination of insects that proved protein or sugar sources reduces ant foraging in an area, very important for this species.
Treatment: Ant bait products in granular, liquid or gel formulations can be affective, and carbohydrate baits may be preferred.