Spring is here, and people aren’t the only ones who enjoy the improving weather. Odorous house ants have been looking forward to the change in weather and they would love nothing more than to march right into the shelter of a home or building. Locating theses colonies and treating them properly early in the year is critical for gaining year-long control and reducing call-backs in the late spring and summer months.
Odorous house ants are similar to Argentine ants in that their colonies go through periods of expansion and contraction. In the winter, colonies contract and form massive populations in a small area (ex. Underneath driveways, sidewalks, and other secure areas). In late winter to early spring, depending on your location, colonies will then begin to expand and set up satellite colonies. This coincides with their mating season, and homeowners will often notice winged adults, called alates, walking along foraging trails or coming out from expansion joints or even baseboards and crown molding if there is an interior infestation.
As a PMP, one critical thing to note when doing an inspection in early spring is odorous house ants trailing into homes. Be on the lookout for trails going into subarea vents or cracks in stucco and the foundation. This is important because typical sprays used for exterior perimeter treatments are repellent to ants and may trap them on the inside of a house. It is extremely difficult to treat this small, trapped colony fragments and often leads to call-backs. If you do notice ants trailing into a home, using baits and a non-repellent product on both the interior and exterior is generally the most effective solution. When baiting on the exterior of a structure, be careful not to place baits in direct sunlight as this will lead to breakdown much quicker. Instead, try to find shaded areas where ants are trailing and use a non-repellent around the bait to force trailing ants to cross the liquid material before they arrive at the bait.