There are several types of white grubs that feed on the roots of lawn grasses. All of them can cause severe damage if left untreated. Grubs live and feed in the soil. It’s easy to miss them as they gradually cut the roots out from under your lawn until brown patches begin to appear and the grubs are finally discovered. Pull back the turf if you suspect grubs. If the lawn pulls up easily (like new sod), you may find white grubs in the top inch or so of the soil.