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Top 10 Pests: Odorous House Ant

Profile of odorous house ant
Odorous house ant profile

Illustration by J. MacGown, Mississippi State University

Odorous House Ant

Scientific Name:
Tapinoma sessile
Formicidae (ants)
Hymenoptera (ants, bees, wasps)
U.S. Distribution:
Throughout the U.S.




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


Match the Shape and Size Match the Color
Odorous house ant profile showing basic shape
Odorous house ant worker
  • Worker is 1/16 to 1/8 inch long (2.2-3.2 mm)
  • Single small node, but hidden by base of abdomen
  • 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
  • Brown to black
Illustration © Pinto & Associates Photo by Neil Reimer, Hawaii State Department of Agriculture


Look-alike Pests

Look-alike Pest Differences

Argentine ant (Linepithema humile)

Node large, NOT hidden by abdomen; stale, musty 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
Ant tending a large group of aphids Trailing odorous house ants along baseboard
  • Feeds mainly on sweets, tends aphids and mealybugs on plants and feeds on honeydew and plant juices
  • Feeds also on seeds, live or dead insects, and greasy foods like meats, cheeses, oils
  • Outdoors: nests in soil under stones, logs, patios, debris piles; also under bark, in plant cavities, in animal nests
  • Indoors: nests in wall voids, under floors, around heaters and hot water pipes; also in crevices behind base-boards, cabinets, window sills, etc.
  • Worker follows trails along foundations, sidewalks, tree branches, baseboards, and carpet edges
  • Colonies can be large with many queens
  • Has rotten coconut odor when crushed
  • When alarmed, worker runs erratically with abdomen raised
  • Swarms from May to mid-July
  • May move indoors when honeydew supply drops, in fall, or during rains

Photo by Marlin E. Rice
Iowa State University Extension

Photo © Pinto & Associates

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