Milky Spore Kills Japanese Beetle Grubs (Larva)

Most insecticides only kill adult Japanese beetles. In order to interrupt the life cycle of the Japanese beetle, it’s important to also kill the young grubs.

Japanese beetle grubs live underground. The eggs were laid there by their mothers and the grubs develop a few inches beneath the surface for up to a year while they are developing.

Even if you kill the adult beetles with seven dust or similar insecticide, you still have the new batch of Japanese beetles growing underground. Unless you kill them, they will hatch into adults during the next Japanese beetle season.

That’s where milky spore comes into the equation. Milky spore is the perfect insecticide for killing Japanese beetle larva because it targets them specifically and doesn’t affect other insects in your garden.

Japanese beetle grubs are susceptible to milky spore disease. Milky spore powder will cause the grubs get that disease and die before they have time to grow and become adults beetles.

I recommend using a combination of milky spore and another insecticide in order to target both the adult and juvenile Japanese beetles. Diatomaceous earth and seven dust are both great products that kill adult Japanese beetles.

A dual approach like this is the best method to disrupt the life cycle of the insect, you are most likely to experience greater success at eradicating Japanese beetle infestations this way.