Pestgon FactSheet
“ If they fly they die…if they crawl they fall”

ANTS: Argentine (Iridomyrmex humilis)

Description:
The most common structure-infesting ant, in Southern California, is the Argentine ant. They are small, a little more than an eighth of an inch long. They are light brown to shiny black and are often seen actively traveling in trails in large numbers.

Biology:
The Argentine ant is the most persistent and troublesome ant in our environment. Pestgon, Inc., has noted that any other ants are only an occasional nuisance. Argentine ants are very aggressive and will drive out other ant species from their territory. They nest and proliferate in damp soil of landscapes, under rocks, ground covers, walks and even in a crack of a concrete slab. They also commonly nest in sheaths of palm trees and under plastic sheeting covered with decorative landscape bark. When aphids are present on the landscape plants, they harvest the honeydew secretions and tend the aphids as caretakers and protectors. Argentine ants develop huge colonies with endless trails going to and fro in and around structures, invading everything in an occupied building in search of food. Entomologists at the UC Riverside, have told Pestgon, Inc., that the huge colonies are actually just one monstrous, super colony covering all of Southern California. That is because, unlike other ants, Argentine ants readily accept each other, from colony to colony. They are particularly fond of sweets. Their prodigious numbers can be in the thousands in a lunchroom, kitchen or food area and they can readily find food in any office environment. When they do, they bring an army of scavengers. These ants gain access through the most minute cracks and openings and will travel up trees and shrubbery, even telephone wires to enter a building.

Economic Impact:
The fear of having thousands of ants show up in a lunchroom, kitchen or workspace is intolerable and can cause an immediate response if even one ant is seen. The presence of an ant in our home, office or work environment seems to trigger an emergency alarm in most people! Pestgon, Inc., has found that Argentine ants are at times attracted to electrical switching equipment, computers, and control devices and can die in large numbers causing a shut down of sensitive communication equipment.

Additional Links:
http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7411.html