Visible Ant Trails Indoors

You can, and the ants you see will die, but the colony will not. With odorous house ants, spraying the trail often makes the colony split into several new nests, so you end up with more trails than you started with. The trail is the route. The nest is the target, and the most useful thing you can do before an inspection is leave the trail alone so it can be followed.

Because the route is marked with scent and it leads to something the colony wants. Wiping the counter removes the food for a day but not the scent on the edges the ants follow, and the nest sends new workers along the same line. Until the entry point and the nest are dealt with, the spot will keep drawing traffic.

Usually closer than you expect. Sugar ants nest in mulch beds against the foundation, under pavers and stones, inside wall voids and under the slab. A trail that runs outside through a window gap points to an outdoor nest. One that disappears into a wall or floor crack and never reaches outside points to a nest inside the structure. The inspection follows the trail to find out.

Size and timing tell you. Sugar ants are about an eighth of an inch long, dark, active in the daytime, and smell like rotten coconut when crushed. Carpenter ants are several times larger, usually black, most active at night, and are found near wood rather than food. Carpenter ants mean damp wood somewhere in the house, which is a different problem.

Heavy rain floods shallow nests in the mulch and soil, and the ants move to dry ground, which is often your house. The same thing happens in reverse during a dry spell, when ants come inside for water. A colony that only shows up with the weather is nesting outside near the foundation, and that is where the treatment should be aimed.