4954 N. Shamrock Place, Tucson, AZ 85705

Odorous House Ant

Tapinoma sessile

Odorous House Ant

Physical Features

Odorous house ants get their name from the strong odor released if they are crushed.  These dark brown to black insects have workers that are 1/8 inch long.  They have 14 teeth with the first two teeth being enlarged at the tip of the mandible.  Key identifying features is an uneven thorax and a hidden node on the petiole.

Life Cycle

Complete Metamorphosis
Odorous house ants live in large colonies numbering up to 10,000 ants with multiple queens.  The ant will complete its development from egg to adult in 5-9 weeks during late spring and summer.  Times for each stage are 11-26 days for eggs, 13-29 days for larva and 10-28 days for pupa.  Workers and females will live for several years.  Males die within a few days of emerging.  New colonies are formed through both nuptial flights and budding behavior.


  • Diet: Prefer sweets(honeydew excreted from plants) but will feed on dead or live insects.
  • Activity: Workers are active 24 hours a day. They are active inside year round. More active in spring and summer outside.
  • Preferred Climate: Temperatures ranging from 50-90 degrees.
  • Defense: Produce 4-5 generations a year and spread in multiple ways aiding in successful colony survival.
  • Cautions: Pungent smell excreted when crushed
  • Home Invasion: These pests often enter the home from the outside which needs to be inspected even when you are discovering activity only on the inside. Nests will be found in soil often along the base of trees. Inside they will be in wall voids, beneath floors, and other voids.

Helpful Hints

  • Keep trees trimmed so branches do not touch house and give a highway into the home.
  • Caulk cracks and crevices where they may be able to enter the home.
  • Keep pet food and food in pantries tightly sealed.
  • Good sanitation practices help eliminate potential food sources.
  • Regular pest control maintenance can be helpful in preventing infestations.

Interesting Facts

Odorous house ants often will coexist in bee colonies.  Bees are not negatively affected and the ant benefits from the heat bees produce.


Odorous house ants do not sting or bite but can become annoying, traveling indoors in large numbers.

Nesting Sites

  • In soil under stones, patio blocks, mulching plastic
  • Can nest in homes in wall voids and under floors