Synonyms and other taxonomic changes
Older name Iridomyrmex humilis, also Linepithema humilis (Linepithema is neuter, so humile is the correct form)
Explanation of Names
humile: Latin for "low, lowly, small, slight"
Humilis also means humble. Most Iridomyrmex, the genus in which this was orginally described, have iridescent green, blue, or purple reflections, so the name may refer to the "humble" (non-reflective) coloring of this species.
one of two species in this genus in North America
worker usually uniformly light to medium brown (can seem almost black if not viewed up close); body slender; head oval to triangular-shaped; mandibles with two large apical teeth followed by series of denticles; alitrunk
dorsum normally lacking erect hairs; petiole erect
[adapted from description by Missipppi State U. - see Internet References below]
across southern United States (from North Carolina to Florida, west through the gulf states to the coast of California. The only limit to their range is freezing temperatures and lack of water.
mostly neotropical distribution; native to Argentina and Brazil
nests in soil, rotten wood, standing dead trees, refuse piles, bird nests, bee hives, under pots or stepping stones, and many other places - sheltered or exposed
Year round. Will often invade homes when weather outside is too cold, too wet or too dry, so may be more obvious at some times than others.
Omnivorous. Especially fond of sweets, but will eat anything
Winged queens mate once with a winged male, after which they can continuously produce fertile eggs for as long as 10 years- until death. Unlike most ants, several productive queens of this species can share the same colony, with one or more leaving with some of the workers to form a new colony when it gets crowded (this is known as "budding").
The grublike larvae are fed and tended by the workers, pupate, then emerge to join their sisters in the colony (worker ants are all sterile females).
Thought to have first arrived in the United States in coffee shipments in New Orleans around 1891.
A major pest in United States for several reasons: able to nest in diverse habitats, produces great numbers of individuals due to many reproductive queens in a colony, eats large variety of food (omnivorous diet), coexists amiably with other colonies of same species, exterminates competing native species of ants wherever they occur, and invades homes in large numbers in search of food and water.
When established in an area, the number of individuals is mind boggling, with large files of workers running up and down trees, on fences, on the ground, and everywhere else; considered one of the most persistant and troublesome of house-infesting ants.
[adapted from text by Missipppi State U.]
This ant once was exceedingly abundant in New Orleans and other Gulf Coast cities, but declined after arrival of Solenopsis invicta. Now, this originally South American species is the most abundant ant in urban and suburban, coastal, southern California, almost to the exclusion of other ant species.
Forelius species have a different dental array on mandibles
Tapinoma sessile lacks erect node on petiole
live adult images
(Alex Wild, myrmecos.net)
preserved adult images
at high magnification, plus description of worker, distribution, and biology (Mississippi State U.)
preserved adult images
and other information (AntWeb, California Academy of Sciences)
plus biology, ecology, control, etc. (Wayne Armstrong, Palomar Community College, California)