Tiny soil mounds are probably earthworm castings (11-17-08)

I have had several calls recently from homeowners concerned about tiny mounds of dirt all throughout their lawns. After a few minutes of discussion describing the size and condition of these tiny piles of soil, the conclusion usually is that they are the castings of earthworms.

In most cases there should be no reason for alarm. Earthworms in moderate numbers are beneficial to the lawn. They tunnel through the soil providing pore spaces for air, water and nutrients to move freely and help develop healthy turf with a strong root system.

Occasionally, however, their numbers increase tremendously and the casting become so numerous that they can create a muddy situation that distracts from the beauty of the lawn as well as tracking of mud into the house. High numbers of earthworms may also attract moles and armadillos onto the lawn to feed on them.

While no one advocates applying insecticides to control earthworms since they are so beneficial, but some products that are used to control grubs can suppress earthworm populations. The best advice is that if they are not creating any serious problems consider these tiny mounds of soil as nothing more than nature’s fertilization.

Published November 17, 2008

Dr. Wayne Wells is an Extension Professor and Turfgrass Specialist. His mailing address is Department of Plant and Soil Sciences, Mail Stop 9555, Mississippi State, MS 39762. wwells@ext.msstate.edu