White Grub is the common name given to the larvae of several species of scarab beetles. The most common of these are June Beetle, European Chafer and to a lesser extent Japanese Beetle. These larvae are 2 – 4 cm long, “C” shaped, white larvae with a brown head at one end. White grubs are usually found in the top few inches of soil in the lawn and feed on grass roots. These pests are a favourite food for raccoons and skunks emerging from hibernation which dig and destroy lawns while foraging.

Both are a type of Scarab Beetle. But the difference is in their life cycles and when they do their damage.

European Chafer go through their life cycle in one year. Adults emege in May, mate and lay eggs which hatch into larvae and feed on grass roots through the summer, these overwinter and again feed heavily in the following spring before pupating into the adult beetle.

June beetle pupate from larvae (emerge as adults) in May and June, mate and lay eggs in the lawn which hatch into the first instar larvae, these first instar larvae feed on the roots of the lawn until fall and then develop into the second instar. These overwinter and spend the next summer as second instar larvae which do the most damage before developing into the third instar larvae. The third instar larvae overwinter once more and spend a short time feeding on the roots before pupating into the adult beetle in May/June. Damaged lawns can often be seen through entire neighbourhoods in three year intervals with this species, with the second instar doing the majority of the damage.

Nematodes are microscopic parasitic worms which infect the eggs and larvae of June Beetle, European Chafer and Japanese Beetle.

After application, the nematodes immediately get to work. Upon finding a grub, they can enter it through various body openings or directly through the body wall. Once inside, it is not the nematode that actually kills the pest, but the toxic bacteria inside the nematode's gut that is the real weapon – symbiotic bacteria, that when released inside an insect or lafrvae, kill it within 24 - 48 hours by causing blood poisoning. Beneficial Nematodes release the bacteria in order to create food and a hospitable environment for their own reproduction. As the food resources within the dead grubbecome scarce, the nematodes exit and immediately begin searching for a new host. As long as there is a suitable host, the nematodes will continue to survive and parasitize. Nematodes can be active in the soil under favourable conditions for 60 to 90 days.

Nematodes are recommended for use in Ontario as a biological control for white grub in the fall (OMAFRA and university of Guelph). Green Circles can make recommendations about dealing with this invasive pest. Call 416-993-5296 or sign up on page 2 of this season's contract.