The buzzing of a June bug may be a sign of spring, but they are also a sign of root-destroying grubs to come. June bugs, chafer beetles and Japanese beetles are all members of the scarab beetle family and all lay eggs in late spring or early summer. These eggs hatch weeks later and the grubs begin their destructive feeding immediately, digging deep to hibernate when winter comes before rising again to resume eating the tender roots. Then ,they form a pupae for a time before emerging as a beetle, restarting the cycle. Some beetles have a one-year cycle, others have a life cycle spanning multiple years, but all can be effectively controlled without resorting to chemicals.
Lift a section of turf where the affected area meets healthy grass. If the turf does not lift easily, use the shovel to gently cut into the sod and lift it. Severely damaged turf will pull up easily. Count the number of c-shaped larvae in the section. Five or more per square foot is a sign of a serious infestation; less than five will not usually harm a healthy lawn and may not provide enough hosts for the nematodes to thrive.
Prepare the nematodes according to the packaging type. Live nematodes, usually packaged in damp media like sponges or soil less mixes, need special care. Never let them dry out or expose them to bright sunlight. Dormant nematodes -- often packaged with a high number of dead nematodes -- are usually granulated or mixed into a gel and sold off a shelf. Follow the package directions and dilute as necessary.
Water the lawn well to bring the grubs to the surface and provide a damp environment for the nematodes. Pour the Hb solution into the hose-end sprayer. Choose a cloudy day or an overcast evening and spray the lawn thoroughly; sunlight will sterilize and eventually kill nematodes within seven minutes, according to Green Methods, a biological pest control website. Do not spray when temperatures are above 90 degrees Fahrenheit.
Water the lawn again. This second watering will push the nematodes into the soil where the grubs are waiting. The nematodes will be immediately active if live specimens were used, and the first grubs will die within a few days. Keep in mind that chilly conditions will send the nematodes into a dormant state; when temperatures rise again in springtime they will resume hunting for the beetle larvae.