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Species Tapinoma sessile - Odorous House Ant

Another small ant on the nest of Formica exsectoides - Tapinoma sessile - female

Small Black Ant with Wings in Oregon Bathroom - Tapinoma sessile - male

Classification

Kingdom Animalia (Animals)

Phylum Arthropoda (Arthropods)

Subphylum Hexapoda (Hexapods)

Class Insecta (Insects)

Order Hymenoptera (Ants, Bees, Wasps and Sawflies)

No Taxon (Aculeata - Ants, Bees and Stinging Wasps)

Superfamily Formicoidea (Ants)

Family Formicidae (Ants)

Subfamily Dolichoderinae (Odorous Ants)

Tribe Tapinomini

Genus Tapinoma

Species sessile (Odorous House Ant)

Synonyms and other taxonomic changes

May be a complex of 4 or so cryptic species

Explanation of Names

Tapinoma sessile (Say 1836)

sessile 'stalkless,' in reference to the appearance of the gaster. In fact, the petiole if there, but it is small and lacks a node

Numbers

Antennae 12-segmented. Palp formula 6,4. Mandibles with 10+ teeth, apical, subapical and 4th from apex notably larger than the rest. Visible gastral tergites 4.

Size

workers 2–3 mm, alates 4–5 mm

Identification

The low, nodeless petiole distinctive, may not be readily visible but clearly seen here

Range

s.Canada to n.Mexico, coast to coast

Habitat

Generally, any mesic or moist (but infrequently flooded) habitat(1); virtually ubiquitous except in hot deserts (only in oases), cold alpine forests (but found in alpine meadows), or above timberline. Very abundant indoors in most of the US and so.Canada, less so in the Sunbelt.

Season

Active early in spring, often in kitchens

Food

Sweets and scavenged protein and fats.

Life Cycle

Has distinct spring and summer forms, larger and darker individuals overwinter, smaller and paler ones are more abundant during the "dog days". Fly late spring.

Remarks

Alates are reared in spring, not uncommonly in wall spaces or window frames of houses, but naturally in the upper portions of leaf piles, under bark, etc.

Internet References

Species page(2)

Works Cited

1.	Ants of the Southeastern United States by Joe A. MacGown

2.	AntWiki

Contributed by tom murray on 19 November, 2006 - 4:30pm
Additional contributions by Beatriz Moisset, Vox Sciurorum, ceiseman, James C. Trager, v belov, Harsi S. Parker
Last updated 14 August, 2025 - 11:25pm

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