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How to Manage Pests

Key to Identifying Common Household Ants

Argentine ant — Linepithema humile
Subfamily: Dolichodorinae

Argentine ant worker
Argentine ant characteristics

Identifying characteristics

  • Workers are all the same size, small, 1/8-inch long
  • Uniformly dull brown
  • Petiole with 1 erect node
  • Thorax uneven in shape when viewed from side
  • Musty odor emitted when crushed


  • Feed on sweets, fresh fruit, and buds of some plants
  • Tend honeydew-producing species
  • Forage for sweets and oils in homes
  • Travel rapidly in distinctive trails along sidewalks, up sides of buildings, along branches of trees and shrubs, along baseboards, and under edges of carpets
  • Colonies may split in spring and summer when queen and workers move to new site; not antagonistic toward each other

Nest type and size

  • 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
  • Millions of ants per colony with multiple queens and many subcolonies

See also, Argentine ant quick management tips.

Statewide IPM Program, Agriculture and Natural Resources, University of California
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