Problem: Earthworms (Lawn)
Earthworms feed on dead roots and stems and are usually an indication of fertile soil. They prefer moist, medium- to fine-textured soil that is high in organic matter. They are seldom found in dry, sandy soil. Although earthworm castings-small piles of soil-may mar the appearance of the lawn, and earthworms may damage new seedlings, their activity improves the soil in several ways. Their movement from the surface to underlying soil helps mix the organic matter on the top with the soil below and reduces thatch accumulation. Their channels in the soil improve air and water movement through the soil. The castings also help improve the soil structure.
Earthworms are beneficial to the soil, so control measures are not required. Break up the mounds of soil with a rake or a vertical mower, or treat with a light power rake to even the soil surface.