Numerous ant species are well known indoor pests in Louisiana, and while most of these species only pose a nuisance within homes, a few species are potentially dangerous to humans. The red-imported fire ant is the ant pest species best known for inflicting medically significant stings, but Louisiana is home to other potentially dangerous fire ant species. For example, the native southern fire ant (solenopsis xyloni) can be found throughout the southern states where their stings have landed people in the hospital, and have even resulted in death. The tropical fire ant (Solenopsis geminata) can also be found in the south, especially the Gulf Coast states where this species has been known to inflict medically significant stings to humans.

The southern fire ant is the most common native fire ant species in the country, and workers of this species can be recognized for their reddish-yellow head and upper body, and black abdomen. Workers range in size from 2 to 6 mm in length, and their bodies are quite hairy, especially on the abdomen. Historically, southern fire ants have been common indoor ant pests in Louisiana, but recent years have seen invasive Argentine ants displace southern fire ant populations in the south. Despite this, southern fire ants remain prevalent in Louisiana where they frequently appear in great numbers in areas where Argentine ants have been successfully eradicated.

Tropical fire ant workers have square-shaped heads, they are orange to reddish-brown in color, and they are between three and eight mm in length. This species used to be abundant in the Gulf Coast states where it was a common household pest, but they have been largely displaced by their invasive red-imported fire ant relatives. However, tropical fire ants can still be found in Louisiana on occasion, and while they are similar to red-imported fire ants in appearance, they are not nearly as dangerous or aggressive to humans.

Have you ever encountered red-imported fire ants within your home?