Grubs are the larvae of any of several insects. Japanese beetle grubs and European chafer grubs cause the most problems for homeowners. Lawn and garden products for grub control are either chemical-based poisons that kill the grubs and other life in the soil, or they are organic controls that are safe to use around children and pets even until the day of harvest in the garden.
Organic Grub Control
Two main types of organic treatment for grubs are milky spore and beneficial nematodes. Both are safe and natural and can be applied even when children or pets play on the lawn immediately after treatment. They are not poisonous substances.
Benefits of Organic
Organic treatments target grubs and are not harmful to earthworms or beneficial insects. Organic treatments for grubs are effective and multiply as the season progresses. They last for many years, because the organic treatments are live organisms that reproduce as they attack and kill the grubs. Fall is the best time to treat for grubs because they are rapidly feeding to store energy for winter.
Milky spore is a natural grub control treatment. Grubs feed on roots, and they are infected when they eat milky spore bacteria that has attached to the root of a plant (grass or other). The grub becomes a host for the bacteria to reproduce. When the host is depleted the bacteria move to other roots and infect the next grub.
Milky spore comes in a chalky carrier powder. Apply it with a drop spreader in a grid pattern over the lawn at a rate of one teaspoon of powder every four feet. Each teaspoon of powder contains over a million bacteria. Do not rake or mow after application and wait at least 48 hours before watering the area. After rainfall or watering, the bacteria have settled into the soil and will spread.
Milky spore disease only affects grubs. The treatment is not toxic to beneficial insects, pets or humans.
Beneficial nematodes are microscopic worms that feed on specific host grubs. When you purchase nematodes, the species of nematode and targeted pest are listed on the package. Nematodes come in a carrier powder. Nematodes are easy to apply by mixing them in a watering can and sprinkling them over the area you want to treat. You can also apply them to a broader area by mixing them in water in a sprayer and covering the area. Nematodes rely on water to help them move through the soil. Apply them in the evening and water them in well. They will have all night to disperse before the sun dries the soil in the morning.
Nematodes attack and feed on grubs, multiplying in the grub as they do so. When the host has been decimated, they move on to find another.
Chemical Grub Control
Chemical grub control products usually contain carbaryl (Sevin) or trichlorfon (Dylox)as "curative" treatments to be applied in the spring or fall when grubs are actively feeding. During the summer phase imidacloprid or halofenozide are the "preventative" chemicals. These are all dangerous poisons. Do not use them near ponds, water sources, or wells. They will also kill butterflies, bees, ladybugs, praying mantis and other beneficial insects. They are toxic to humans and pets.