The grubs you typically find in your vegetable garden are larvae of various beetle species, including the scarab, Japanese beetle, May beetle and chafers. Measuring anywhere between 1/2 to 1 1/2 inches long, white grubs require three years to reach maturity. Although seemingly innocuous, white grubs feed on any part of the plant growing underground, including the roots and in the case of potatoes or carrots, the vegetable itself. You have several safe, effective ways to control grubs without harming the growing vegetables.
Till the soil with a hoe or mechanical rototiller before planting in the spring and again in the fall. Bringing the grubs to the surface leaves them vulnerable to predators, including birds and skunks, according to the Virginia Cooperative Extension.
Slip on work gloves, and pick up the grubs by hand. Sift through the tilled soil and manually remove all the grubs. This is an effective solution if the problem isn't widespread. Toss the grubs into an outdoor garbage can to ensure they don't reinfest your garden.
Introduce beneficial predators to your garden. Parasitic wasps prey on the grubs, helping keep their numbers in check, according to the Virginia Cooperative Extension. The University of Rhode Island also recommends introducing Heterorhabditis bacteriophor, a type of beneficial nematode, to your garden at a rate of 1 billion per acre. Beneficial and predatory insects are available through nurseries and gardening centers.
Mix 2 tablespoons of neem oil and 1 gallon of water in a plastic spray bottle. Spray the infected soil and plants with the mixture. Neem oil is an effective insecticide used to control the grub population, according to Michelle Niedermeier, an integrated pest management coordinator for Penn State and the Pennsylvania Department of Agriculture. Neem oil is a derivative of the neem tree and a natural insect repellent and pesticide.