Basements that are damp and moist attract earthworms. Two species of earthworms are found in North America, according to Earthworm Digest. Earthworms require a steady body temperature to maintain a low respiration rate and burn less energy, making them seek cool, moist areas, like basements. Although earthworms are not harmful, there are preventative measures you can take to stop earthworms from entering your basement and causing a nuisance for you and your family.
Seal any openings in the basement walls to prevent earthworms from getting in through cracks. Remove any dirt or debris from the outside of the walls. Add a cement primer to the walls with a paint brush. Follow the manufacturer's instructions.
Allow the primer to set. Use caulking to fill in the cracks and holes. After the caulking is dry, cover the walls with a cement sealant.
Check the water drainage around the basement walls, doors and windows. Make sure no downspouts or gutters are overflowing, causing excessive water around the basement walls.
Check windows and doors for cracks that allow moisture into your basement. Repair the cracks and make the seals tight to stop earthworms in your basement.
Avoid placing flower beds and large objects, such as garbage cans, that hold moisture and attract earthworms close to your basement walls or doors. Moist, shaded areas provide a location for earthworms to live and breed. Eventually, they find a way into your basement.
Use a dehumidifier in your basement to remove moisture from the air. The humidity should be kept under 65 percent, according to North Dakota State University. Earthworms do not like dry climates and will avoid entering your basement if it is dry.