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Top 10 Pests: Argentine Ant

Argentine ant worker and queen
Argentine ant worker and wingless queen

Photo by P.Banko, U.S. Geological Survey

Argentine Ant

Scientific Name:
Linepithema humile (formerly Iridomyrmex humilis)
Formicidae (ants)
Hymenoptera (ants, bees, wasps)
U.S. Distribution:
Southern half of continental U.S., California, Hawaii, and isolated populations as far north as Washington State, Maryland, and Illinois



This page has three tables, (1) Identification, (2) Look-alike Pests, and (3) Biology and Habits.


Match the Shape and Size Match the Color
Profile of argentine ant
Argentine ant worker
  • Worker is 1/16 to 1/12 inch long (2.2-2.6 mm)
  • Single upright node
  • Antenna 12 segmented, without a club
  • Thorax uneven, without spines
  • No stinger, and no acidopore (a circle of hairs around the orifice at tip of abdomen)
  • Uniform color
  • Light brown to dark brown
Illustration by J. MacGown, Mississippi State University Photo by Neil Reimer, Hawaii State Department of Agriculture


Look-alike Pests

Look-alike Pest Differences

Odorous house ant (Tapinoma sessile)

Node tiny, hidden by abdomen; rotten coconut odor when crushed
Crazy ant (Paratrechina longicornis)
Legs very long in relation to body; anal opening circular and surrounded by a circle of hairs (acidopore); no odor when crushed


Biology and Habits

Match the Food and Site Match the Habits and Damage
Ants feeding on sugar and sweets aerial view of neighborhood
  • Inside, Argentine ants favor sugar, jelly, cookies, candy, soft drink spills, and other sweets
  • In nature, they feed on sweet plant secretions and "tend" aphids and mealybugs to feed on honeydew
  • Also feed on meat, seeds, and other insects
  • Rarely nest in a single, defined site; usually many different nests connected by trails
  • Nests are typically outside in moist locations under boards, rocks, refuse piles, sidewalks or slabs, in moist leaf litter and mulch, or sometimes in tree holes, bird nests, or beehives
  • In spring and summer, a large nest may be split into many small nests
  • Worker ants can squeeze into very tight spaces; even getting into refrigerators
  • A colony may include tens of thousands of workers plus hundreds of queens spread throughout the landscape
  • "Super colonies" of cooperating ants can cover hundreds of miles
  • Stale, musty odor when crushed
  • May move indoors during cold, wet weather, when honeydew supply declines, or during droughts or excessive rainfall
  • Mating swarms rarely seen; mating takes place in the colony. Winged males are seen occasionally at lights
  • Can forage day and night in long, safari-like ant trails
  • Destroy other ants, including fire ants
Photo © Pinto & Associates Photo © iStockphoto/Dainis Derics

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