Nematodes - White Grub Control

White grubs are a common pest in Ontario lawns.  These grubs are the larvae stage of the Scarab beetle that feed on the roots of grasses and other plants.


This results in the wilting and death of grass in patches on the lawn. Wilted grass can be pulled free easily due to the devastation of the root system.  Another indicator of grubs is damage done by animals such as skunks, raccoons and other animals digging up the lawn to eat the grubs.


To get rid of or prevent white grubs, nematodes are available in Ontario as a biological control.  Nematodes are a parasite of white grubs that come in several strains.  The fastest acting strain is Stienernema, which usually kills insects within 16-24 hours. Nematodes kill host larvae and within 2 or 3 weeks, will reproduce a new generation of up to 200,000 more Nematodes.


Nematodes help control more than 250 insects including Cutworm, Root Weevils, Wire Worms, Fungus Gnat Larvae, Corn Borers and of course, Japanese Beetle Grubs.  They seek out insects by sensing an increase in temperature or by smelling Methane Gas. They work by releasing a bacteria in the grub which causes it to die.


Nematodes are harmless to people, pets and other wildlife.  Children and pets can play on the lawn immediately after application.  



Nematodes should not be applied until the ground temperature is at least 10 degrees C. To avoid the effects of solar radiation and temperature extremes, application in early morning or early evening is recommended. For the best protection against grubs, Nematodes should be applied in mid-May to mid-June and again in late-August to mid-October.


Nematodes should be kept in the fridge until you are ready to apply them. It is best to release them on a cooler, cloudy or rainy day.  Place the Nematode sponge into 1 gallon/ 4 litres of water, creating a concentrated solution of Nematodes.  After discarding the sponge, the concentrate will need to be diluted with water using a fertilizer applicator, a dial sprayer, a pressure sprayer (Nematodes can withstand 300 psi) or a watering can. Fill the dial sprayer with the Nematode solution and attach the garden hose, ensuring that there is no screen attached to the hose inside the applicator for the Nematodes to get stuck in. The Nematode solution must be kept agitated while being applied as it will settle. After applying Nematodes, keep the lawn moist for 3-5 days to ensure effectiveness.