How to Kill Grub Worms in Garden Soil

Nearly every gardener has encountered white grubs infesting garden soil and the lawn surrounding it. These white grubs are immature Japanese beetles. Adult Japanese beetles lay their eggs in soil during the summer, and the grubs hatch from the eggs. The grubs begin feeding on the root system of just about any plant they can find, including grass in your yard or the roots of flowers and vegetables in your garden. Though it is difficult to completely eradicate all of the grubs in your garden, you can make life a lot harder for them.


Step 1

Attract robins to your garden and yard. Robins are songbirds that feed mainly on earthworms and grub worms. Since they do not eat seeds, most traditional bird feed will not lure robins to you. Make a mixture of peanut butter and suet, and place it outside in or around your bird feeder. Robins will also eat pieces of bread, hamburger meat, cherries, strawberries and cheese.

Step 2

Avoid killing moles. Moles can damage your garden and yard, but they also love to eat grub worms. If you see mole tunnels around your garden but you haven't noticed much damage from them, let them stay. The moles will usually eat their fill of grubs in one area, and then move along to another spot.

Step 3

Remove any decaying plant debris on the ground in your garden. Very young grub worms will eat decaying plant matter and plant roots. Having less food options for them will lower the chances they invade your garden.

Step 4

Apply nematodes to the garden soil. Nematodes are small parasitic worms that will seek out grubs, bore their way inside their bodies and kill them. Purchase nematodes at garden stores. Mix them with water and spray them on the soil.

Step 5

Sprinkle Milky Spore powder in the garden soil. Milky Spore powder contains a bacteria that will kill the grubs but is not harmful to humans, animals or plants. The best time to use Milky Spore powder is August, when the grubs are likely to be closest to the surface. Another benefit of Milky Spore is that it can kill and repel grub worms for several years.