Japanese beetles and masked chafer beetles appear in the spring and early summer. The beetles like moist, sunny landscapes and these are the types of lawns where most grub damage is seen. The female beetle burrows into the soil and lays her eggs during the middle of summer. The white grubs in the lawn are the larvae stage of the beetles. When the eggs hatch, the larvae start eating the tender roots of the grass. The damage to the lawn has begun.
One of the first signs of a potential problem with grubs in the lawn is beetles on the plants in the garden. A Japanese beetle can lay 40 to 60 eggs in a summer. Treating the adult beetle problem keeps fewer female beetles from laying eggs in the soil. Fewer eggs means fewer grubs and less damage to the lawn.
The feeding larvae eat grass roots in an irregular pattern causing wilting and dead spots in the grass. When you start seeing brown patches in the lawn, pull back a section of the turf and dig down about an inch or two. Look for the C-shaped white larvae. Treat your lawn if you spot more than six grubs in a 1 square foot area. Always try to identify the beetle larvae so you are applying the right treatment.
Skunks and raccoons like the fat white grubs and will dig up the lawn to find the morsels. Night time damage of the lawn showing signs of digging and burrowing is a good indication the animals are searching for the white grubs in your yard. You can reduce the damage done by the grubs and hungry animals by introducing nematodes into the lawn. Nematodes infest the grubs and kill the larvae before they can do more damage.