Chafer beetle grubs attack grass roots. Skunks sometimes tear up lawns looking for grubs to eat. (CBC)

As Ontario's ban on lawn and garden pesticides looms, experts are encouraging gardeners to try using a parasitic worm to mow down grass-destroying grubs.

Ontario announced that it will ban more than 300 pesticide products in the category known as cosmetic pesticides, by 2009 over health concerns, and the ban is expected to include chemicals used by many gardeners to kill the chafer beetle grub.

The grubs attack grass roots and are sought after by skunks, which uproot lawns in search of the succulent snacks.

The pesticide ban doesn't mean gardeners will have to put up with the grubs and skunks ravaging their grass, but they will have to adapt, says Mark MacKenzie of Appleseed Organic Lawn Care in Ottawa.

Mark MacKenzie says Ontario's imminent pesticide ban means many gardeners will have to learn new techniques for controlling grass-destroying grubs. (CBC)

"A lot of people are going to have to learn new techniques and new methods, but there are excellent organic methods out there," he said.

MacKenzie said he has been using organisms called nematodes as a "biopesticide" against chafer beetle grubs for the past 10 years.

"They're microscopic worms, and once they infest the [grub's] body, they will inject a bacteria that's is harmful to the grub and kill the grub," he said, adding that the bacteria are "completely harmless to any other life form — [humans] or pets or skunks."

The worms are dormant while in cool storage but become active when exposed to water and sprayed onto the ground or lawns. One application costs about $80, MacKenzie estimated.

According to Ontario's Ministry of Agriculture, Food and Rural Affairs, biopesticides, which can be either chemicals or organisms, are becoming increasingly available but should only be used in organic gardening or farming as a last resort.

The ministry instead recommends keeping plants resistant to pests by ensuring they are healthy.

In the case of grass, MacKenzie recommends making sure it never gets cut shorter than three inches, which will allow it to grow deep roots to reduce grub damage.