By Carolyn Faulkner

Two of the most common earthworms found in our area are redworms and nightcrawlers.  Redworms (eisenia foetida, also known as red wiggler worms) are shallow dwellers, living in the top 12 inches of the soil.  These are the worms most commonly used for vermicomposting, a method of creating rich garden compost by keeping worms in a covered bin and feeding them decomposing organic material such as kitchen vegetable waste, garden clippings and leaves. 

The second type of worm you are likely to find in your yard is the nightcrawler.  These worms burrow underground during the day and emerge above ground at night to deposit their castings.  Nightcrawlers are vertical burrowers capable of digging down as deep as 8 feet in moist soil.  They can grow up to 14 inches in length and live as long as 6 years, if not eaten by a predator.   Worm predators include birds, rats, mice, moles, toads, turtles, snakes, and even ants.

Nightcrawlers may leave small cone-shaped piles of “dirt” (called middens) in the middle of a lawn or orchard.  These consist of worm castings, which are rich in nutrients and organic matter. In this process, soil particles along with digested organic material are coated with mucous from the worms’ digestive tracts.  The result is pure fertilizer for your garden. 

Both types of earthworms are actively engaged in improving the soil. When they burrow they help to mix soil nutrients together, while also decomposing organic matter in the soil. Their burrows create tunnels for plant roots, water, air and nutrients.  They also increase the water-holding capacity of the soil and are beneficial in reducing thatch buildup.  And they can eat their weight in decaying plant matter each day.

Earthworms are mainly seen at night, when watering frequently takes place, or after rainy days.  They like moist soil which makes it easier for them to burrow, and, for the nightcrawler, provides an opportunity to move to a new location. 

On the down side, an “invasion” of worm castings can have an unsightly effect on the appearance of a lawn.  Several approaches may be taken to address this issue, but applying pesticides is not one of them.  Pesticides will kill other beneficial insects, and may affect a natural predator.  Instead, try these management alternatives: 

• Pick up the castings by hand and use them in your garden as fertilizer
• Rake the castings, smoothing out the surface so they are not seen
• Mow turf at a higher level which may hide the castings
• Drive worms deeper into the soil by changing your irrigation schedule so the top    layer of soil dries out between irrigations. 

And remember that the role of the earthworm is mainly beneficial.  Earthworms are nature’s rototiller. 

Want to go a step further, and learn how to create beautiful, rich, nutritious compost from kitchen and garden scraps with help from worms? Attend our June 6th workshop on “Black Gold” Vermiculture, part of the Master Gardeners 2025 Spring Workshop Series. All workshops are free, but registration is required. For full workshop descriptions and to register, visit our website.   

Plant Sale Tomorrow -- Saturday, May 3, 2025 at our Demonstration Garden at Patrick Ranch. For more information and a partial plant list, visit our website.

UC Master Gardeners of Butte County are part of the University of California Cooperative Extension (UCCE) system.  To learn more about us and our upcoming events, and for help with gardening in our area visit our website. If you have a gardening question or problem, email the Hotline at mgbutte@ucanr.edu or leave a phone message on our Hotline at 530-552-5812. To speak to a Master Gardener about a gardening issue, or to drop by the MG office during Hotline hours, see the most current information on our Ask Us section of our website.