Why Late Summer/Early Fall is the BEST Time to Treat for White Grubs

August 10, 2017 | Common Garden Pests

White grubs are a common turf and lawn pest, and beneficial nematodes can be a very effective (and safe!) control. However it is important to treat at the right time of year, based on the white grubs’ life cycle, to ensure good control.

Since almost all scarab beetles have a life cycle of one year, it is important to treat at the right time to ensure the nematodes can kill the larvae (also known as white grubs) and prevent new adults from emerging. Typically the adult beetles lay eggs in the summer which then hatch within a few weeks. The newly hatched larvae feed throughout the summer and fall before overwintering in the soil. The larvae will continue to feed in the early spring before pupating and eventually emerging as new adults. Treating in late summer or early fall is ideal, as that is when the smaller, young grubs are most susceptible to nematodes. There is also usually a short window for application in early spring before the grubs get too big and pupate, but that is a narrower window and can be difficult to time properly.

See the life cycle (in this example of a Japanese beetle) pictured below:

Below is an image that shows how beneficial nematodes kill white grubs:

Our recommended product for all types of white grubs in Heteromask, although Scanmask is also effective. For more information on how beneficial nematodes kill nematodes and other FAQs, see this blog post.