In the spring and fall skunks and raccoons forage for their favourite meal, the white grub larvae. Circular indents in your lawn are the work of skunks, while raccoons tend to peel or rip up the sod. The damage caused by raccoons and skunks is the most obvious, but is only secondary to the damage caused by the grub larvae. Grub larvae live deep in the soil until spring or fall when they rise to the surface of your lawn to eat the roots of the grass. Two other species are the European chafer and the Japanese beetle.
Damage is often the most severe in spring and fall when the moisture in the soil is very high.
Here's some information about common insects and their grubs, how to control them and how to discourage wildlife. These beetles emerge from the soil during late May and early June. At dusk they feed and mate on the foliage of broad-leaved trees and shrubs. At daylight they burrow into grassy areas and the females lay their eggs. The eggs hatch in a few weeks and for the rest of that summer the larvae feed on the roots of the plants and other decaying organic matter.