Chafer Beetle: Defending your turf

Steve Whysall, 2006-03

Chafer beetle infestation is destroying B.C. lawns, but here are some ways you can fight back

    Does your lawn look as if someone just ran over it with a rototiller? Is the grass all churned up and turning yellow as it dies from having had its roots ripped from the ground?

    In other words, is your lawn a total mess?

    Well, you probably know by now that these are all classic signs of an infestation of European chafer beetles.

    Thousands of lawns throughout the Lower Mainland have been destroyed, or are about to be destroyed this month, as crows, raccoons and skunks tear up turf in an excited search for tasty chafer grubs.

    The crows and raccoons are actually doing a very good job of pest control. They are nature’s environmentally correct agents, digging and eating the juicy grubs before they have a chance to turn into a mature beetle that flies off to reproduce and perpetuate the cycle of destruction.

    Unfortunately, in the process, the chafers are also killing lawns and leaving them looking as if they’ve been over-enthusiastically power-raked or rototilled.

    And the invasion of the chafer is far from under control. What we are seeing now is only the beginning. Although the problem is most visible in New Westminster, Burnaby, parts of Coquitlam and the east side of Vancouver, experts predict the bug will eventually travel to the west side of Vancouver and the North Shore.

    “Just because you don’t see a problem with your lawn doesn’t mean you don’t have chafers,” says Peter Isaacson, pest management expert with the Canadian Nursery Landscape Association.

    “What you need to do is cut a small square out of your lawn — a foot [30 by 30 cm] by 5 cm [two inches] deep — and look for grubs. If you find more than five or 10, you have a chafer problem.”

    The chafer wasn’t always here. It first surfaced in B.C. in New Westminster in 2001. “We think it got here in a some nursery stock shipped from the east where it has been since the 1940s when it came from Europe,” says Isaacson.

    Could the New Westminster infestation have been contained if strong pesticides had been used right away to eliminate it?

    Isaacson says he doubts it. “By the time we knew it was here, it had spread throughout the area. It would have been very difficult to contain.”

    So what are homeowners to do when they find they have a chafer infestation and their lawn has been ripped up?

    Isaacson says various tests were done in New Westminster to come up with an effective and environmentally acceptable control method. “We found that the best form of prevention was quality lawn care,” says Isaacson. Lawns that are diligently cared for — raked, dethatched, aerated, reseeded, fertilized, watered (appropriately), and not mown too severely — are far less vulnerable to chafers than lawns that are neglected, he says.

Ironically, this finding flies in the face of the philosophy of anti-lawn advocates who encourage homeowners not to waste time fertilizing and recommend that lawns be left to turn brown and go dormant in mid-summer rather than watered to keep them lush and green. Experiments have been done using nematodes — microscopic organisms — that can be watered into the soil in summer. These organisms attack the developing chafer larvae and can dramatically reduce the population.

However, tests revealed that there is only a narrow window of opportunity to use nematodes effectively, usually in the third or fourth week of July or the first week of August.

    The ground needs to be moistened in advance and ideally the nematodes should be applied in the evening or on a cloudy day.

    Fifty million nematodes — Heterorhabditis bacteriophora is the most effective kind — are available from garden centres for $79.99 a packet. Two packets are recommended to treat a lawn of 1,400 square feet.

    Prevention through quality lawn care is the recommended first line of defence, but once a lawn is infested and has been ruined by ravaging crows and raccoons, homeowners are faced with a different set of options.

    Ripped-up grass should be raked up and disposed of. Isaacson says homeowners should check with their municipality about disposing of soil containing chafer grubs. “The last thing we want is to have chafers transported to parts of the city where they don’t have the problem.”

    Once the area has been raked clear, new topsoil should be put down and the lawn re-seeded. This should not be done in June when chafers (in their flying beetle form) swarm at dusk and lay new eggs. They are often mistaken for bees.

    Having re-established the lawn, it is important to implement a good maintenance program that involves watering twice a week (about 2.5 cm a week) and mowing once a week, cutting grass no shorter than 5 or 6 cm.

    When an infestation is particularly bad, it may be necessary to call in a professional landscaper to do what Isaacson calls “a chemical cleanup”.

    This involves using one of two pesticides — Merit or Sevin — which are applied at different times, Merit being a systemic insecticide, and Sevin a chemical that attacks the grub’s nervous system.

    Instead of replacing a lawn with a lawn, another option is to use plants such as salal, thyme, heathers, ornamental grasses, sedum, vinca and Dutch white clover as groundcovers. For more information on the chafer beetle, contact your local municipality.

    swhysall@png.canwest.com 

    

THE CHAFER’S YEAR

Here’s a guide to the European chafer beetle’s year-round activity and what action you can take.

JANUARY-MARCH: Grubs feed on grass roots. Raccoons, skunks and birds tear up turf to find the white larvae.

Action: No control of chafer at this time. You can confirm that it is a chafer problem by turning over a 30-cm square of lawn.

APRIL-JUNE: Grubs enter a resting stage in May, before emerging as adult beetles in June. Adults swarm at dusk to mate and lay eggs.

Action: Repair and replace lawn in April-May. With a severe infestation, consider insecticide application by a professional.

JULY: Eggs laid in soil in June hatch, and small grubs begin to feed on grass roots.

Action: Apply nematodes during third week of July. Apply at the rate of 750,000 per square metre. This, along with good lawn care, is the most successful long-term method of control.

AUGUST-SEPTEMBER: Small grubs in soil continue to feed on grass roots, causing grass to wilt or die in patches.

Action: Maintain lawn care, watering appropriately. In September, apply slow-release fertilizer. Continue to mow grass no shorter than 5 to 6 cm.

OCTOBER-DECEMBER: Grubs move close to the surface and continue to feed on grass roots. Raccoons, skunks and birds start to rip up lawn to find grubs.

Action: No control of chafer possible. Minimize skunk and crow damage by replacing or patting down clumps of grass immediately after they have been pulled up.

 

Also note:

  • Vancouver Parks board says to fight beetle plague with worms
  • Vancouver residents can buy a $35 package of nematodes at the city's Grow Natural Day on July 22 at the Champlain Heights Community Centre, or by visiting This Site
  • THIS INFESTATION HAS NOW REACHED WEST VANCOUVER