Their presence is not sufficient evidence to conclude that there is a nest in your home. You may be able to make a more accurate determination based on when you first see carpenter ants. For example, if you find carpenter ants in your home within several days of the first warm, sunny weather in March or April, that suggests the ants are coming from a nest in or very near the building. If your first sighting of carpenter ants does not occur until weeks or months after the onset of spring weather, those carpenter ants may be coming from an outdoor nest and are only foraging for food. However, it is also possible that they could be from a satellite nest establishing an indoor colony.
Carpenter ants produce large numbers of queens and males during late summer.
They emerge from nests the following year in spring for their nuptial flights. After mating, queens search for suitable sites to begin new nests. Once they land, their wings break off and each queen starts construction of a new nest. When carpenter ant nests are indoors, mating swarms become trapped inside. Finding large numbers of winged ants indoors is a sure sign that an indoor nest exists and may give the approximate location of the colony.