FAQ: How to Kill White Grubs with Nematodes

White grubs are a very common insect pest. Not only do the grubs cause damage to turf and lawns, but adult beetles can also cause damage to a wide variety of plants. Late summer and early fall is the best time to treat with nematodes to kill white grubs before next spring!

What are white grubs and how do I know if I have them?

White grubs are the larval stages of a wide variety of scarab beetles, including Japanese beetles, northern masked chafers and rose chafers. White grubs feed on plant roots, causing patches of dying, brown grass. A bad infestation can cause grass or turf to be so damaged it can be pulled back like a carpet.

Which product do you recommend for treating white grubs?

Heteromask is our preferred product for white grubs, but Scanmask is also effective.

When can I treat for white grubs?

Treating in late summer or early fall is ideal, when the young grubs are small and most susceptible to nematodes. There is also usually a short window in early spring, before the grubs get too big and pupate. Most white grubs have a one-year life cycle, but May and June beetles take 2 to 3 years. To see how the life cycle sets this timing, read Why late summer/early fall is the best time to treat for white grubs.

How many nematodes do I need for my grub infestation?

We recommend about 25,000 nematodes per square foot.

How should I apply the nematodes?

Focus treatment on sunny areas of your lawn or turf, or on any areas that show signs of grub damage. Heteromask comes in a spray formulation, and you can use the Nema-Jet, a hose end sprayer or a watering can (for smaller areas) to apply. We include detailed directions with our products, or you can view the full directions on our website.

How often do I need to apply?

One application typically lasts about a year, and often longer. The best way to know when to treat again is to watch for grubs coming back.

Are nematodes safe to use around children? Will they harm my bees, earthworms or any other beneficials?

The nematodes in BioLogic's products are naturally occurring and completely safe for people, pets and plants. They are environmentally friendly and non-toxic. They pose no danger to humans, and you do not need to worry about run-off. They are compatible with other beneficials like bees, earthworms, ladybugs and praying mantises!