While white grubs are known to cause damage to lawn in the form of irregular brown patches, they can also bring an added problem in the form of predators that use grubs for food. Grubs are the larval form of beetles and are found underground eating roots. The best method to eliminate pest problems caused by grubs is to eliminate the grub population.
Birds can be a pest when looking for food. Many birds use grubs found in lawns as a main food source. The largest birds, blackbirds and crows, can do considerable damage by their foraging. Damage from these two birds includes scratching into lawns with their feet and digging into the lawn with their beaks. Starlings are less of a problem unless they begin to arrive in large flocks where fecal waste and noise can become a problem.
Moles feed on grubs and create tunnels underneath the soil. These tunnels can be visible from the surface by the raised ridges formed from the tunnel ceiling. These ridges can dry out causing brown lawns and irregular streaks. A residual effect to plant roots and bulbs occurs from rats and field mice that use the mole tunnels to travel.
Raccoons dig for grubs leaving multiple holes throughout the lawn. This pest arrives when the grub concentration is still low and will remain as long as the grub population remains. Look for sections of sod that appear torn apart because this is a sign of raccoons ripping through sod to find grubs underneath the roots. Raccoons are nocturnal feeders so the damage will not be apparent until the next day.
Skunks look for grubs in the same fashion as raccoons by digging during the night. Usually where there are skunks, there are also raccoons since they both hunt for the same food. This can cause extensive damage to your lawn and other areas. While raccoons tear sod up, skunks dig holes the size of golf balls to reach grubs. Skunk problems are apparent when their distinctive smell is found.
Voles are the smallest of the pests looking for grubs. While voles are mostly vegetarian, they will eat grubs if their supply of roots, tubers or bulbs are in short supply. Voles cause damage to lawns similar to moles in that they dig networks of tunnels under the lawn.