Pest Control St. Louis

Argentine Ant

Latin Name: Iridomyrmex humilis

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

Color: dark-colored

Other: It is also 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 stomach by a thin pedicel, a thin stalk.

Where can they be found? Outdoors in soil, under wood, 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 common ant in southern California is the Argentine ant (Iridomyrmex humilis). This ant can also be located in the low eastern US area. As reported by Wild (2004), this species was originally described in the genus Linepithema by Mayr in 1866; therefore, the proper binomial ought to be Linepithema humile. It is a tiny, dark-colored ant about 3 mm (1/8 inch) long that invades homes searching for food and water. They are specially 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 can be really well adapted to urbanized areas of the US with mild climates and well-watered gardens. They pose an important threat to native wildlife by upsetting delicate food webs. They are specially formidable attributable to their aggressive behavior and the huge size of their colonies which can literally "team up" with other colonies.

If you live in southern California, you in all probability have seen endless single file columns of uninvited six-legged guests walking through your home. They follow a pre-marked pheromone "scent" trail initially laid down by scouts who were looking for goodies in your pantry. Although they choose to outdoor life-style, they primarily enter houses for food and water. They are like sweets, tuna, syrups (even cough syrup), juices, eggs, dead spiders and rodents, puke, feces and almost any other living tissue they can find. They are fundamentally scavengers and they play a valuable role in the natural ecosystem–but preferably in Argentina. In hot, dry weather they often times search your house for water, including restroom faucets 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 very cold, they once more 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 active, they moved across the southern half of the US. A single colony may contain 10,000 female workers, and there may well be many colonies around your home; the complete number of ants could reach a million. Although they cannot sting, they can bite; nonetheless, they are simply 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 just 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 mom bird and killing the helpless young. One possible redeeming quality about these little warriors is that they might 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 related with the same DNA. They apparently will accept ants from different colonies as members of their gigantic family. In fact, Argentine ants from different colonies will actually "team up" and attack together in vast swarms. They simply outnumber and overpower their enemy.

Argentine ants have become a difficult 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 fascinating red ant while maturing in San Gabriel Valley, and I can personally testify that it provides 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 factor in the demise of California harvester ants, but an even greater factor leading to the liquidation of native ants and coast horned lizards is the aggressive Argentine ant. Evidently the horned lizard is not like Argentine ants, and is in fact attacked by them in enormous swarms. Colonies of Argentine ants need a damp area to survive, and have not invaded a few 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 particularly 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 protected 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 possibly 20 or 30 queens. They get along 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 greater. 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. In fact, a queen from San Diego would probably be accepted in a colony elsewhere in California.

Argentine ants (Linepithema humile): A wingless queen and several workers. Although these ants are merely 3 mm long, they are 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 cargo in New Orleans. U.S. populations are so intimately linked 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 because their DNA has developed much greater variation. Neighboring colonies may fight each other, despite the fact that they are simply 200 yards (200 m) apart. Also there are quite a few native predators in Argentina, including fungal leeches and bacteria. The narrow genetic variability that has kept all the California populations on friendly terms may eventually backfire owing to abnormal inbreeding. Perhaps some day these ants might not have the genetic variability to adapt to a changing environment.

How To Control Invasions of Argentine Ants"

Empty your trash often and ensure your property has no 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 even get into screw-top jars without seals. They follow the spiral threads until they're inside!

Try not to use 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