Even the name “grub” implies a gross and unwelcome parasite—some slimy thing that wriggles inside shadowy places, just begging to be squished. In the case of lawn grubs, an aggressive and persistent line of defense is necessary to keep your lawn and landscape intact. Lawn grubs—larvae of the Scarab family of beetles—live just underneath the soil, feeding on the roots of turfgrass and other kinds of ornamental plants. They are most active in late July and August, and their voracious appetites can leave your lawn in a state of extreme disrepair. Their constant feeding causes brown patches in grass, spongey lawns, and the sudden death of plants and flowers. Lawn grubs also attract other kinds of animals like skunks, raccoons, and birds to infested yards, which can compound the damage.
To check for grubs, inspect your lawn for telltale signs of grub damage: dead spots, spongey turf, discoloration, and so forth. If you notice anything irregular, check the soil by digging up a 12 inch wide, 3 inch deep plot of dirt. In the upturned dirt, look for white, C-shaped insects. A healthy lawn can tolerate some grub activity—about ten grubs per square foot. If you see more than that, you might have an infestation. Unfortunately, it’s hard to manage a grub infestation after it’s already established itself. For best results, spray a grub control pesticide in late summer when the larvae are close to the surface of the ground feeding on roots. Winter and spring treatments are not as effective because the larvae aren’t feeding as much and so they generally stay farther underground. August is considered the “goldilocks” month for grub control. In August, grubs are not yet fully grown (and thus more vulnerable to pesticides) but they are feeding vigorously right next to plant roots.