Experts and BHG readers answer.
night crawlers in my lawn
The mounds of earthworm castings can be annoying in a lawn, but it's a sign of a healthy lawn. The earthworms aerate the soil and convert decaying organic matter into humus that the plants can use. While you could use an insecticide to kill the earthworms, we don't recommend doing so. Instead try raking out the castings to spread them throughout the lawn. They are a beneficial topdressing for the grass.