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

• 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

Odorous house ant (Tapinoma sessile)

• 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