Treating ants in the winter

Dr. Ryan Neff, West Coast Technical Field Specialist, MGK

For much of the U.S., the winter season means ant activity is declining. But for some regions, winter brings an unexpected increase in ant calls. While many non-native ants hunker down to wait out the winter, some native species, like odorous house ants (Tapinoma sessile, or OHA), can pop up inside homes. During the warmer months, treatment typically involves locating exterior satellite colonies followed by some combination of liquid residual treatments and baiting. However, in the winter, these satellite colonies often contract into single colonies inside wall voids, attics, subfloors and other areas inside structures to escape the cold.

Controlling OHA in these situations can be difficult, especially when customers only see a few ants here and there. To make matters worse, customers often will self-treat or wipe up foraging ants and their pheromone trails. This makes it more difficult to locate colonies.

Pre-baiting with syrup or honey can aid in locating the colony, although it’s a tough sell to get customers to do this. Once colonies are located, you can use a variety of treatment methods to eliminate them. Dusting, liquid residuals applied with compressed air sprayers or aerosol-generating machines, aerosols, or baits can be effective, depending on the situation.