Chafer Beetles and Lawn Grubs in BC: How to Identify, Treat, and Repair Your Lawn

If your lawn has developed brown patches that pull back like loose carpet, or you're finding it torn up by crows, raccoons, and skunks overnight — you're probably dealing with lawn grubs. And in BC's Interior, the culprit is almost always the European chafer beetle.

This guide covers everything you need to know: what chafer beetles actually are, how to confirm you have them, when and how to treat, and how to repair your lawn once the damage is done.

What Are Chafer Beetles?

The European chafer beetle (Amphimallon majale) is an invasive pest that has spread across much of BC over the past few decades. The adult beetle is unremarkable — a small brown flying insect that emerges in early summer, mates, and lays eggs in your lawn. It's the larvae, or grubs, that cause the damage.

Chafer grubs are white, C-shaped larvae that live just below the soil surface and feed on the roots of your grass through late summer and fall. A healthy lawn can tolerate a small grub population. A heavy infestation destroys the root system entirely — leaving turf with nothing anchoring it to the soil.

The secondary damage is often worse than the grubs themselves. Crows, skunks, and raccoons are highly effective at detecting grubs underground and will tear up large sections of lawn overnight to get to them. If you're waking up to a lawn that looks like something dug it up — something did.

Signs of Chafer Beetle Damage

Grub damage doesn't always look like grub damage at first. It's easy to blame drought, disease, or poor soil before you find the real cause. Here's what to watch for:

Brown patches that don't recover with watering The most common early sign. If sections of your lawn have turned brown and aren't responding to rain or irrigation, grubs may have eaten through the root system. Drought-stressed grass recovers when watered. Grub-damaged grass doesn't — because the roots are gone.

Turf that lifts like a rug Grab a corner of a brown patch and pull. If the turf peels back easily with little resistance, the roots have been severed by grubs feeding just below the surface. This is the clearest confirmation short of digging.

Animal digging Crows pecking in a methodical line across your lawn, or skunks and raccoons tearing up chunks overnight, is a strong indicator of grub activity. These animals have an excellent sense of smell and are following the food. The digging damage can look more dramatic than the grubs themselves.

Increased beetle activity in early summer European chafer adults emerge in June and July, swarming trees and shrubs at dusk. If you're noticing small brown beetles flying around your yard in the evening, eggs are likely being laid in your lawn within days.

How to Confirm It's Grubs

If you suspect grub damage, dig a small section of turf — roughly 30 cm x 30 cm and about 10 cm deep — in an affected area. Count the grubs you find. In BC:

• 0–5 grubs per square foot — low population, most healthy lawns can tolerate this
• 6–10 grubs per square foot — moderate infestation, damage likely
• 10+ grubs per square foot — heavy infestation, treatment strongly recommended

The Chafer Beetle Life Cycle (And Why Timing Matters)

Understanding the chafer beetle's life cycle is the key to treating it effectively. There's only a short window each year when treatment works — miss it and you're waiting until next season.

June – July: Adult beetles emerge, mate, and females lay eggs in the top few centimetres of soil — preferring warm, sunny lawns.

July – August: Eggs hatch and young grubs begin feeding near the soil surface. This is the treatment window. Grubs are small, close to the surface, and most vulnerable.

September – October: Grubs grow larger and move deeper into the soil to overwinter. Treatment at this stage is largely ineffective.

Spring: Grubs move back toward the surface briefly before pupating into adults. Damage from the previous year becomes fully visible as snow melts.

The takeaway: if you're going to treat, it needs to happen in late July to early August. That's the window, and it's narrow.

How to Get Rid of Grubs in Your Lawn

Nematodes — The Most Effective Treatment

Beneficial nematodes (Heterorhabditis bacteriophora) are microscopic roundworms that parasitize and kill chafer grubs. They're the most effective available treatment for chafer beetles in BC, and they're safe for people, pets, and the environment.

How to apply:

• Purchase nematodes from a garden or farm store — they're sold refrigerated and have a short shelf life, so apply promptly
• Water your lawn thoroughly before applying
• Mix nematodes with water according to package instructions and apply with a hose-end sprayer or watering can
• Water again immediately after application to drive nematodes into the soil
• Keep the lawn moist for at least two weeks after application — nematodes need moisture to survive and move through the soil

When to apply: Late July to mid-August in BC's Interior is the ideal window — when grubs are young and feeding near the surface. Soil temperature should be above 15°C for nematodes to be effective.

Realistic expectations: Nematodes typically achieve 50–80% reduction in grub populations. This is significant but not a complete elimination — one treatment rarely solves a heavy infestation entirely. Repeat applications in consecutive years are usually needed to get the population under control.

Cultural Controls

A few lawn care practices make your lawn less attractive to chafer beetles and more resilient against grub damage:

Raise your mowing height. Chafer beetles prefer to lay eggs in short, warm turf. Keeping your grass at 8–10 cm makes your lawn a less attractive egg-laying site.

Reduce irrigation in June and July. Female chafer beetles favour moist soil for egg-laying. Cutting back on watering during this period — if rainfall allows — can reduce how many eggs are laid in your lawn. This is a supplemental strategy, not a solution on its own.

Overseed with resistant grass varieties. This is a longer-term play but an important one. Certain grass species and varieties are more tolerant of grub feeding because they develop deeper, denser root systems. More on this below.

What About Chemical Treatments?

Options for chemical grub control in Canada are limited compared to the US — several products available across the border are not registered for use in BC. If you're considering a pesticide-based approach, check with your local garden centre or agricultural supply store for currently registered products in your area, and always follow label instructions carefully.

How to Repair a Chafer-Damaged Lawn

Treating the grubs is only half the job. Once you've got the population under control — or even while you're managing it — you need to repair the damage. Bare and thinned patches left alone invite weeds to move in fast.

Step 1: Remove Dead Turf and Loosen the Soil

Rake out dead grass and debris from damaged areas. Loosen the top few centimetres of soil with a rake or hand cultivator — this improves seed-to-soil contact and gives new grass a better start.

Step 2: Amend the Soil if Needed

BC Interior soils often run alkaline and can be compacted. If damaged areas have been heavily grub-fed, the soil structure may be compromised. A light topdressing of compost worked into the top layer helps restore organic matter and improve growing conditions for new seed.

Step 3: Reseed with the Right Grass Mix

This is where product choice matters. Not all grass seed performs the same against repeated grub pressure. Reseeding with a blend that includes deeper-rooting, more resilient grass varieties gives your lawn a better chance of withstanding future infestations — even if grub populations aren't fully eliminated.

Our Chafer Resistant Seed Mix is specifically formulated for this problem. It combines deep-rooted, high-endophyte Turf-Type Tall Fescue with Microclover® — a blend that naturally deters chafer grub infestation once established, while also improving drought tolerance and fixing nitrogen from the air (which means less fertilizer needed over time). It's available in 2 kg bags and works for both new lawns and overseeding damaged areas.

Step 4: Apply a Starter Fertilizer

New seed needs phosphorus to germinate and establish strong roots. Use a starter fertilizer — one with a higher middle NPK number — rather than a standard nitrogen-heavy lawn fertilizer. High nitrogen at germination stresses new seedlings.

Step 5: Keep It Moist

New seed needs consistent moisture to germinate — typically 10–21 days depending on grass variety and soil temperature. Water lightly and frequently until the new grass is established, then gradually transition to deeper, less frequent watering to encourage deep root growth.

When to Reseed

Fall is the best time to reseed in BC's Interior. Soil temperatures are still warm enough for germination, competition from weeds is lower, and the cooler conditions suit cool-season grasses. If damage is severe and you're reseeding in spring, be prepared to manage weed pressure alongside the new growth.

Frequently Asked Questions

How do I know if I have chafer beetles or a different pest? The C-shaped white grub test is your best confirmation. Chafer grubs have a distinct raster pattern (a V-shaped row of spines on their underside) that distinguishes them from other white grubs. If you're not sure, bring a grub into our store in Kamloops or Merritt — we're happy to help identify it.

Can I treat chafer beetles in spring? By spring, grubs have moved deeper into the soil and are preparing to pupate — they're largely unreachable and not feeding actively. Spring treatment is generally ineffective. The treatment window is late July to mid-August when grubs are young and near the surface.

Will my lawn recover on its own without treatment? Light infestations — fewer than 5 grubs per square foot — may not require active treatment if your lawn is otherwise healthy. Heavy infestations will continue to worsen year over year without intervention, and the secondary animal damage alone can be severe enough to warrant treatment even at lower grub counts.

How long does it take for nematodes to work? Results aren't immediate. Nematodes need 2–4 weeks to establish and reduce grub populations noticeably. Keep the lawn moist during this period. You may still see some animal digging in the weeks following application as surviving grubs are detected.

Are chafer beetles a problem every year? Yes, chafer beetles complete a one-year life cycle and re-infest lawns annually. A single treatment reduces the current population but doesn't prevent next year's adults from laying eggs. Consistent management over 2–3 years — combined with reseeding with resilient grass varieties — is the most effective long-term approach.

Is chafer beetle damage covered by any programs in BC? Some BC municipalities have offered nematode subsidy programs in the past, particularly in the Lower Mainland where chafer pressure has been severe. Check with your local municipality to see if any programs are currently available in your area.

The Bottom Line

Chafer beetles are a long-term management challenge, not a one-season fix. The most effective approach combines nematode treatment in the late summer window, cultural practices that make your lawn less attractive to egg-laying adults, and reseeding with grass varieties that are better equipped to handle grub pressure.

If you're not sure where to start — whether that's identifying the damage, finding the right nematodes, or choosing the right seed mix for your lawn — stop by and ask. We've been helping BC Interior homeowners with exactly these kinds of problems since 1947, and we're happy to point you in the right direction.