Chafer grubs feed on grass roots
Image: Chafer grubs feeding on grass roots

Thousands of lawns throughout Canada are being ruined as crows, raccoons and skunks tear up turf to get to tasty chafer grubs.

This is old news to most homeowners – chafers have been with us for the past 14 years – but there are still many people who apparently do not know what is going on, so here is a little background and advice.

European chafers first arrived in New Westminster in 2001, hidden in nursery stock shipped from Eastern Canada, where they have been a problem since the 1940s.

The crows, skunks and raccoons love to dine on the white grubs which are feeding on the roots of grass.

But the crows, skunks and raccoons are actually doing a good job of pest control.

They are nature’s agents, digging and eating the juicy grubs before they have a chance to turn into a mature beetle that fly off to reproduce and perpetuate the cycle of destruction.

What should you do to restore your lawn?

Image: Extensive damage on a a lawn caused by the Chafer beetle.

Nothing right now. First, let the crows and raccoons do their job.

Try to stomp back down pieces of turf, if you can, but if the damage is too severe, the ripped-up grass will need to be raked up and disposed of.

Do this later in spring when you can make a better assessment of the overall damage.

Image: Chafer beetle

The best form of prevention is quality lawn care. 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.

Insecticides can often be effective. Although most effective insecticides are now banned by most municipalities and landscapers won’t use stronger pesticides because they themselves are barred from purchasing effective controls due to the new by-laws.

Image: Close up of chafer grubs

A new biological strategy to defeat chafers is to use nematodes – microscopic organisms. These are watered into the grass in summer and attack the developing chafer larvae.

However, 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.

Image: Raccoons often cause extensive damage to turf from feeding on grubs.

This is not inexpensive. Fifty million nematodes — Heterorhabditis bacteriophora— are available from garden centres for about $80 a packet. Two packets are recommended to treat a lawn of 1,400 square feet.

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.

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.

 Source: Vancouver Sun