Most people enjoy the benefits that nightcrawlers have on their yard. They help aerate the soil, and their castings are a natural fertilizer. If earthworms are present, you know you have good, fertile soil. However, the castings that worms leave behind on the surface can be a problem for someone who takes great pride in a perfect lawn.
One of the easiest ways to reduce this problem is to water your lawn less. If the top 1-2 inches of soil is allowed to dry out a bit, worms will avoid that area. They need to stay moist to breathe and so they will burrow down further where the moisture is.
If you live in a naturally wet climate, or have experienced more rain than normal lately, you can rake the castings up. Sometimes the abundance of castings can cause a lawn to yellow in spots because there is too much fertilizer. Raking the castings away before they cause damage could help tremendously.
If you truly have too many worms in your lawn, and you need to remove them, electrical prods might be an agreeable solution. It will bring the worms to the surface so you can pick them up and relocate them, but it shouldn’t harm your lawn.