Active ants are a sign of spring

  • Carpenter ants may become more active in the spring.

    Carpenter ants may become more active in the spring. Courtesy of Chicago Botanic Garden

By Tim Johnson
Chicago Botanic Garden
Posted4/11/2021 7:00 AM

Finding carpenter ants in a home during early warm weather in spring can indicate there is a nest in the home. It is important to try to determine whether the ants are coming from an outdoor or an indoor nest, although this can be difficult.

If you find carpenter ants in your home during winter, late winter or early spring, that suggests the ants are coming from a nest in the building. If you see activity later in the year, it is less clear if the nest is in the building.


Black carpenter ants can vary in size from one-quarter to one-half inch in length. They do not eat wood, but they will create tunnels in it, leaving telltale sawdust behind. They are attracted to wood that is softened by moisture.

Carpenter ants also nest in rotting trees, stumps and boards left on the ground. You will likely need to work with a professional exterminator to eliminate an indoor infestation.

• Finish cutting back perennials and cleaning up garden debris this month. It is best to cut back perennials before they start growing to minimize any possible damage to the new growth.

It can be hard to see new growth on ornamental grasses, so be sure to cut them back before consistent warm weather sets in. If the weather warms up and the grasses are growing, then cut them at a few inches above the ground to avoid the new shoots.

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Be careful of any bulbs that may have started growing. It is best to avoid or minimize walking on ground that is wet from melting snow, spring rains or as the frost is coming out. The soil will generally take longer to dry out during the cooler spring temperatures than it does in summer.

• Begin uncovering hybrid roses in early April by carefully removing mulch from the base. A bamboo stake works well for this task. Leave a small amount of mulch at the base for protection in case of a late hard freeze.

Monitor weather forecast and adjust your timing as need if extended cold periods are predicted. Prune these roses back to live growth (green stems), which, in some years, may leave only 1 to 2 inches of stem.

• Tim Johnson is director of horticulture at Chicago Botanic Garden,

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