Answer: There are several types of grubs, and not all are a concern in the garden. The worst are those which infest our lawns. They may be found in gardens, but usually not in great quantities. These "bad" grubs feed on grass roots and cause serious problems in the lawn. They can feed on other plant roots, but unless the plants are dense, the female is not interested in laying her eggs in the garden. There is another type of grub which feeds on decaying organic matter. One of these is often found in manure piles and may wind-up in a garden when the manure is spread in the garden. This type will also be found in compost piles, another way it can get into the garden. If you reclaimed a former turfgrass area, the grubs might be Japanese Beetle (the destructive kinds of grubs) rather than the compost/manure feeding grub which would not be considered a problem.
If you are not certain that these are debris feeding grubs and want to be certain that your vegetable roots will not be eaten, you can apply granular sevin to the soil according to directions on the label for use in a vegetable garden. Be certain to check these directions and that the product is labeled for use in a vegetable garden before you purchase the insecticide. Sevin is lethal to bees so be careful not to use it on your plants when they are flowering (and therefore attracting bees). Or, you can use milky spore. Milky Spore is a naturally occurring host specific bacterium (Bacillus popillae-Dutky) which targets Japanese Beetle grubs. It works in 7-21 days.
Best wishes with your garden!
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