Improving the cultural practices of your lawn care may help reduce night crawler activity naturally  Night crawlers feed on the thatch layer which is a layer of partially decomposed grass stems, roots, and stems at the soil surface but below
the green vegetation. Thatch is excessive if it’s greater than ¾ inch deep. Aerating and dethathing is a one way to keep your lawn healthy and reduce the amount of food available for the night crawlers. You might consider vertically mowing your lawn. A vertical mower has high speed vertically rotating blades that slice into the turf to reduce thatch and aerate. It will also help break up and smooth out the bumps. This can be professionally done or you can do it yourself with a mower rented from hardware stores or lawn and garden centers. Once this is done, use topsoil or compost and over seed the area.

https://hortnews.extension.iastate.edu/1993/4-28-1993/bumps.html