Pest Control St. Louis

Argentine Ant

Latin Name: Iridomyrmex humilis

Characteristics: It is a tiny, dark-colored ant about 3 mm (1/8 inch) long that invades homes looking for food and water..

Color: dark-colored

Other: It is in addition light to dark brown in color, and it has six legs, as with other insects. The Argentine ants' antennae have twelve segments. The thorax joins the abdomen by a thin pedicel, a thin stalk.

Where can they be discovered? Outdoors in soil, under timber, slabs, debris, mulch, or in branches and cavities of trees and shrubs

Shallow, 1- to 2-inch deep mounds in open, often disturbed habitats, either moist or dry

The most frequent ant in southern California is the Argentine ant (Iridomyrmex humilis). This ant can also be located in the low eastern US area. According to Wild (2004), this species was originally described in the genus Linepithema by Mayr in 1866; therefore, the right binomial ought to be Linepithema humile. It is a tiny, dark-colored ant about 3 mm (1/8 inch) long that invades homes in search of food and water. They are specifically fond of sweets, but will feed on practically any food. They love hard boiled eggs and carry small yellow clumps of yolk back to their nest in endless ant columns.

These ants are exceedingly well adapted to urbanized areas of the United States with mild climates and well-watered gardens. They pose an essential threat to native wildlife by upsetting sensitive food webs. They are especially formidable as a result of their aggressive behavior and the massive size of their colonies which can literally "team up" with other colonies.

If you live in southern California, you likely have experienced endless single file columns of uninvited six-legged guests walking through your house. They follow a pre-marked pheromone "scent" trail first of all laid down by scouts who were searching for goodies in your pantry. Although they prefer the outdoor lifestyle, they primarily enter houses for food and water. They are fond of sweets, tuna, syrups (even cough syrup), juices, eggs, dead spiders and rodents, vomit, faeces and almost any other organic material they can find. They are basically scavengers and they play a valuable role in the natural ecosystem–but preferably in Argentina. In hot, dry weather they often times search your home for water, including restroom taps and drains. I once followed an ant safari into my restroom where they were neatly stacking their precious cargo of tiny eggs inside my toilet tank. They also relish the "honeydew" secretion of aphids, and protect their aphid friends from natural predators. In the fall months as the nights get chilly, they once again seek the warmth and shelter of your cozy home.

The first Argentine ants set foot on U.S. soils in the late 1890's, as coffee ships from Brazil unloaded their freight in New Orleans. Being prolific breeders and constantly on the go, they moved across the southern half of the United States. A single colony might incorporate 10,000 female workers, and there may well be many hundreds of colonies around your house; the entire amount of ants could easily reach a million. Although they cannot sting, they can bite; still, they are only about 3 mm long and there tiny mandibles are too small to hurt humans. But, internationally of insects, these ants are truly a living terror. They're very aggressive and readily overtake other ant species, even ants that are much larger and with powerful stings. Argentine ants are relentless and merely outnumber their adversaries until the enemy colony is destroyed. They even attack paper wasp nests under the eaves of a house, forcing the massive wasps to flee their nests in terror. Even nests of large carpenter bees are no match for these relentless ants. A "killer bee" nest probably could not withstand an invasion of Argentine ants. They also will attack bird nests, driving off the mother bird and killing the helpless young. One possible redeeming quality about these little warriors is that they may attack dry- timber (aerial) termite colonies in your home. I have seen this Lilliputian massacre in a termite infested table in the Palomar College greenhouse.

Most ant colonies are very highly territorial, and will fight different colonies of the same species. Since Argentine ants in the United States originated from the original colonizers in Louisiana, they are all closely linked with the same DNA. They apparently will accept ants from different colonies as members of their gigantic family. In point of fact, Argentine ants from different colonies will actually "team up" and attack together in vast swarms. They only outnumber and overpower their enemy.

Argentine ants have become an important threat to the coast horned lizard (Phrynosoma coronatum) in southern California. The primary food source for these endangered lizards are native harvester ants, particularly the California harvester ant (Pogonomyrmex californicus). I spent many years observing this interesting red ant while aging in San Gabriel Valley, and I am in a position to personally testify that it features a traumatic sting. As of 2006, this large red ant is seldom seen in urbanized areas of coastal southern California.

California harvester ant (Pogonomyrmex californicus), primary diet of coast horned lizard.

Urbanization has certainly been a aspect in the demise of California harvester ants, but an even better factor leading to the liquidation of native ants and coast horned lizards is the aggressive Argentine ant. Apparently the horned lizard is not fond of Argentine ants, and it's actually attacked by them in enormous swarms. Colonies of Argentine ants need a damp area to survive, and have not invaded some of the dry habitats where native harvester ants and desert horned lizards (P. platyrhinos) still live. Of course, they can readily colonize urbanized desert areas inhabited by people. Well-watered gardens with stepping stones and concrete slabs provide the idea living requirements for these ants. In their native Argentina they live under rocks.

Coast horned lizard (Phrynosoma coronatum).

Argentine ants are a terrible nuisance in gardens and orchards because they tend and protect scale insects and aphids. They even carry aphids to the tender buds of your prized roses. In return, the ants consume a sweet secretion from the aphids called "honeydew." In addition, swarms of these ants will invade orchard trees, destroying the fruit crop. This is especially serious in figs (Ficus carica) where the symbiotic pollinator wasps are destroyed.

Metallic green fig beetles (Cotinus texana) gorging themselves inside a fleshy, ripe syconium of the Calimyrna fig (Ficus carica). Although masses of minute, aggressive Argentine ants (Linepithema humile) are also foraging in the syconium (white arrow), the beetles are safe by their tough, impervious exoskeleton. These attractive beetles spend their juvenile larval stage in the earth, often beneath manure piles, compost and haystacks.

According to entomologist David Faulkner, if you've a 10 x10 foot (3 x 3 m ) patio slab, you may have a million or more individuals and perhaps 20 or 30 queens. They interact fine because they're all associated with the original colonizers in Lousiana, perhaps from the original gravid (pregnant) female who arrived there. Workers live a month or more as adults, but queens live up to 10 years or more. With other ants, when the queen dies, the one-queen colony dies because no more ants are being produced. With multi-queen Argentine ants, another queen simply moves in and takes over the role of the deceased queen. As a matter of fact, a queen from San Diego would in all likelihood be accepted in a colony elsewhere in California.

Argentine ants (Linepithema humile): A wingless queen and various workers. Although these ants are only 3 mm long, they're very aggressive and quickly annihilate other ant species, even larger ants with powerful jaws and stings. They overpower other species by their sheer numbers. Argentine ants in the U.S. are descendants of original colonizers that entered Louisiana in the late 1890's, as coffee ships from Brazil unloaded their freight in New Orleans. U.S. populations are so closely related that different colonies with multiple queens can literally merge together into supercolonies. Image taken with Nikon D-90 and 60mm Micro Nikkor AF-S F/2.8G ED Macro Lens using a Phoenix Ring Flash; hand-held at 640 ISO, F-32, 1/125th sec.

In their native homeland of Argentina, different colonies of Argentine ants are not so friendly to one another as their DNA has developed much greater variation. Neighboring colonies may fight each other, despite the fact that they are only 200 yards (200 m) apart. Also the're a great many native predators in Argentina, including fungal leeches and bacterium. The narrow genetic variability that has kept all the California populations on friendly terms may eventually backfire due to extreme inbreeding. Perhaps some day these ants might not have the genetic variability to conform to a changing environment.

How To Control Invasions of Argentine Ants"

Empty your trash often and make sure your home is free of crums and food particles that may attract ants. Make sure that food containers are tightly closed, without residual traces of the food on the sides of containers. These ants can also get into screw-top jars without seals. They follow the spiral threads until they are inside!

Avoid using toxic aerosol insecticides inside your house–unless you don't care about your lungs or your bone marrow.

Try spraying a deodorant detergent (Pine Sol