Seal squirrels out of attics, or they will return


February 11, 2022

Squirrels, raccoons and other wildlife can harbor fleas, too. PHOTO: RAPIDEYE/ISTOCK / GETTY IMAGES PLUS/GETTY IMAGES


Gray squirrel (Sciurus carolinensis) nests are a familiar sight in many neighborhoods across the eastern half of the United States — and parts of the west where this species has been introduced.

The messy clumps of leaves can be spotted high up in trees, especially during the winter months after leaves have fallen. Occasionally, gray squirrels find their way into homes. They can be a destructive pest, especially in attics where they can ruin insulation and chew wires.

Understanding why gray squirrels seek shelter in buildings can help inform the way we perform inspections, and provide insight for clients who struggle to keep them out.

It turns out that leaf nests are not the preferred location for gray squirrels. Cavities inside trees provide better insulation and protection from predators compared to leaf nests. In fact, the survival rate of young is 40 percent lower in leaf nests compared to cavities.

Natural den cavities don’t typically appear in trees until the age of the stand reaches 40 to 50 years, but in neighborhoods, these older trees — especially those that are dead or dying — are removed before they become a hazard to people. Removal eliminates the preferred den locations, leaving no option but leaf nests and voids in buildings.

Jim Fredericks

Jim Fredericks

Given the opportunity, squirrels will readily move into attic spaces. The warm, dry space will create the ideal environment for overwintering and raising young. Because the space is large, as many as eight to 10 squirrels can share the same attic.

Because attics provide such a great place for squirrels to den, make sure entrance holes are sealed once squirrels are evicted. In vents, eaves, soffits and fascia, look for holes the size of a golf ball or larger, and either make repairs or insist that the client have the work done right away. If the entry point is not sealed up, it won’t be long until more squirrels move into your client’s cozy attic.

About the Author

Dr. Jim Fredericks, PHOTO: National Pest Management Association

You can reach Dr. Fredericks, BCE, executive director of the Professional Pest Management Alliance (PPMA), at

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