Grub worms are the larvae of the May or June Beetle.The worms are commonly found in the topsoil of gardens and lawns and feed on the roots of grass, weeds, or vegetables often destroying crops and lawns.
These white grubs found in the surface soil are easily identified by their characteristic "C" shape and reddish-brown head. Grub worms have three pair of legs on the upper body. Soil may show through the lower body giving it a darker appearance. Grubs vary in size from 3/4-inch to 1 1/4-inches in length, depending on the species.
The adults beetles are generally referred to as May or June Beetles, depending on the date which the Beetle takes flight for mating in a given area. The worms range in color and size depending on the species. There are over 200 species of these beetles in North America that grow up to 1-inch in length and are varying shades of brown to black. The outer wings of the beetle are hard and oval-shaped.
Adults Beetles emerge and take flight in the spring, usually in May or June, and lay eggs rolled in a ball of soil. Eggs generally hatch within two weeks and the young grub begin feeding on organic debris in the soil. As the season progresses the grub increase in size and begin to feed on roots. As fall approaches the grub tunnels deeper into the soil to avoid the harsh winter temperatures and emerges again in the spring. The now large grub feeds heavily on young roots at this time.
Grub worms destroy crops by eating away at the roots. An active infestation can cause a lawn to turn yellow and eventually brown as the roots are severed from beneath. In the garden, grubs can easily destroy crops. This happens most often in early spring when plants are actively growing new roots. The worms eat the roots causing the plant to die.
Remove grub worms by hand in early spring when the garden soil is newly-tilled. Dispose of the worms in an area away from the garden. Treat soil with insecticide designed to kill grubs when they are newly-hatched. The grubs are smaller and less resistant to insecticides at this time. Early spring applications to kill off emerging grubs may be effective. Fall applications tend to be less effective as the grubs have already begun to travel to deeper levels of the soil in preparation of winter hibernation.