The symptoms are brown patches where the grass blades are missing and not simply dead. The larvae can be found in silk-lined tubes they have made in the thatch layer. The most common white grub seen in the soil is the C shaped larvae of the May or June beetle. European Chafer larvae have become a serious a problem in lawns. These larvae feed on the grass roots and when numerous can cause dead areas in the lawn.
Symptoms are dead areas in the lawn.
The grass in the affected area can sometimes be easily pulled out. Roll back a section of sod to see how many grubs are under the lawn. If many grubs are found, controls may be necessary. Frequent irrigation may help infested lawns cope with grub populations. Information summarized from the following Michigan State University Extension publications.