Subject: Invasive Argentine Ants
Location: Mount Washington, Los Angeles, California
August 27, 2016
Dating back to our relocation to Los Angeles in 1980, the editorial staff of What’s That Bug? has been plagued by colonies of invasive Argentine Ants, Iridomyrmex humilis. If we had the time to devote ourselves to the elimination of one invasive species in California, it would be the Argentine Ant. They are a pervasive pest species that we have always believed are the same Ants that play such an important role in the magnificent 20th Century novel “One Hundred Years of Solitude” by Gabriel García Márquez when they carry off a newborn baby. Argentine Ants are most troublesome in the summer, during the hottest days when they enter homes to find water, but swarm around cat food, any sweets or fatty foods left out, or any dead bugs that ended their lives as cat toys. We believe they are one of the biggest threats to native species wherever they proliferate. According to Clemson University: “Argentine ants are not native to the United States. They were introduced to the US probably on coffee ships from Brazil and Argentina through the port of New Orleans sometime before 1891. They spread rapidly on commercial shipments of plants and other materials. Now Argentine ants are found throughout most of the southern states and California, with isolated infestations in a few other areas. Argentine ants have been very successful. They are common in urban areas and can nest in diverse types of habitats. They can produce large numbers of offspring and survive on a wide variety of food. They often live on friendly terms with other neighboring colonies of the same species, but may eliminate some other ant species.” Argentine Ants farm Aphids and move them from plant to plant. We have also found Argentine Ants associated with other pestiferous Hemipterans that secrete honeydew. We would love to hear any control methods our readers can provide. Wayne’s Word also has some interesting information, including: “Best Method Of Argentine Ant Eradication Place outdoor ant bait stations such as Terro® along major ant trails in your yard. This is probably better than using insecticidal sprays. Smaller, indoor bait stations are also effective placed along ant trails in your home (out of the reach of children and pets). The active ingredients of Terro® is 5.40 percent sodium tetraborate decahydrate (Borax) which is lethal to ants. This salt upsets their digestive system and causes death due to dehydration and starvation. According to Jonathan Hatch (“How to Get Rid of Argentine Ants” ), dehydration and recrystallization of the ‘boric acic’ (borax?) lacerates the digestive system of ants and their larvae. There are many recipes on the Internet that include mixing borax with a sugary solution. Terro bait stations contain this mixture in convenient disposable plastic trays. It is important for the ants to carry the liquid back to their nest. Borax recipes only contain about 5 percent borax so that ants are not killed immediately. One tablespoon of borax in a cup of water is approximately a 5% solution. You must be patient–this treatment may take several days to a week. In fact, you may need to replenish you bait stations! Some websites state that boric acid is a more effective ant insecticide, but this is debatable. Boric acid is made by reacting borax (sodium tetraborate decahydrate) with an inorganic acid, such as hydrochloric acid (HCl).”
WE cannot say for certain if the Argentine Ants played a role in the death of this Orbweaver, but since Orbweavers are somewhat helpless when they are not in their webs, it is possible that this large spider was overcome by marauding Argentine Ants and killed.