European Chafer Beetle
- What is a European Chafer Beetle?
- Why is it a problem?
- Biology and Life Cycle
- How to tell if my lawn is infested?
- What are my Options?
- How do I Repair my Damaged Turf
- Suggested Links
What is a European Chafer Beetle?
The European Chafer beetle is an introduced insect to British Columbia that has become a serious lawn pest in the Lower Mainland. It was first discovered in New Westminster lawns and boulevards in 2001. Since then, its geographic range has increased in the region. Adult European Chafer beetles (Figure 1) are tan or brown and measure 1.5 cm in length. The larvae (grubs) measure approximately 2 to 2.5 cm in length, are white and C-shaped with tan colored heads and six prominent legs.
Why is it a problem?Chafer beetle infestations can be extremely damaging to lawns. The adult beetles are active at dusk and can be seen clumsily walking across lawns. Although visible, the adult beetles are not a nuisance and do not feed or cause damage. The grubs are the damaging stage. They feed on roots all types of grass, and if food is scarce, may move into vegetable plantings to feed on corn, potatoes, blueberries, strawberries, conifers and other crops. Grub feeding on grass roots weakens and kills grass plants, resulting in large brown and dead patches. Additionally, major damage can occur when crows, skunks, raccoons and other animals dig up the lawn in search of the large, white grubs that are present from September to April. (Figure 3)
Figure 3. Turf damage from vertebrate feeding on grubs.
Biology and Life CycleChafer beetle complete their life cycle in one year which means that their population may rapidly increase if left unchecked. The eggs hatch around mid-July, and the grubs grow and moult twice over 8 weeks. The mature grubs thrive in moist conditions and feed throughout the fall and winter. During the winter they dig down during periods of freezing conditions, but mostly remain within 5 cm of the surface in our coastal BC climate. They feed in the spring until April when they become pupae. Adults emerge in late May and June, fly to nearby tall trees to mate, and subsequently the females drop down to the ground to lay up to 50 eggs each in the soil.
How to tell if my lawn is infested?Chafer beetle infestation is often most visible in the fall through early spring (October-March) when raccoons, birds and other wildlife begin to dig up the turf eager to eat the grubs. Other times of the year, you may notice your lawn:
- Feels “spongy” when you walk on it due to the grubs feeding below (July-September).
- Is wilted or dead and brown and be easy to pull up.
- Has had an abundant moisture in spring and fall and drier weather quickly resulted in the appearance of brown patches.
- Has raccoons, birds and other wildlife digging up grasses and damaging turf.
The only way to confirm the chafer beetle’s presence is through a simple test conducted between September and March. Cut five sample sections of sod that measure 30 x 30 cm (1 foot) to a depth of 5 cm (2 inches), and fold it back. By digging up several test sections in both affected and unaffected areas, you can monitor for grubs while they are near the surface. Generally, if more than 5-10 grubs are found in a 30 x 30 cm square control is warranted to prevent turf decline and damage.
What are my Options?The European Chafer is a pest that cannot be easily eliminated. There are four main controls to address infestations of chafer:
- Maintaining a healthy lawn: Adopt a vigorous maintenance routine involving aerating, dethatching, fertilizing, deep watering, and high mowing. In high traffic areas consider grass replacements such as mulch or paving stones, or use non-grass (alternative) ground covers.
- Raising mowing heights to 6 – 9 cm.
- Installing alternative landscapes devoid of grass: Dutch White Clover, Salal, Ajuga, Vancouver Gold Bloom, Thyme and Sedum. Talk to your local garden centre experts about these ground covers, their needs and what may work best for you.
Beneficial Nematode applications: The use of a biological agent called Nematodes, living microscopic worms that attack the chafer grubs. Nematodes must be ordered, stored and applied all within a very short time period in July for best results. Nematodes require moist soil before and after application to help them travel to the chafer grubs below the lawn surface.
During the third week of July, complete these steps to treat the infestation:
- Pick up your pre-ordered nematodes (heterorhabditis bacteriophora) from your local lawn and garden store. Make sure to keep them refrigerated until the application day - these are living organisms.
- Moisten your lawn well (to the consistency of a wrung-out sponge).
- Apply nematodes on your lawn at a rate of approximately 50 million nematodes per 139 square metres (1500 square feet).This should cover a 33 x 45 foot lawn. Water the lawn again after the application to push the nematodes into the soil.
- Keep the soil moist for two to three weeks after applying the nematodes to ensure best results.This can be done within your lawn watering restrictions.
- You may wish to purchase a water exemption permit to allow for additional sprinkling days. BettleGone or GrubGone (Bacillus thuringiensis galleriae) applications during beetle flight and egg laying. This microbial insecticide has recently been registered for use in Canada for control of European chafer. Contact your licensed landscaper to arrange for applications during the summer months.
All insecticides sold in Canada are reviewed and approved by Health Canada for the use specified on the label. There are a few insecticides registered in Canada for management of European chafer. They are all applied in a similar fashion: as a dilute, high volumes spray to turfed areas, when larvae are small and most susceptible. The soil must be moist at time of application, and it is best to water after the application to move the product into the root zoned. Contact your licensed landscaper to arrange for an annual application in spring or early summer.
How do I Repair my Damaged Turf?Once the European Chafer pupates in the spring or you have taken effective management steps, animals and birds will stop digging for this food source and you can start to repair your lawn. It is recommended that you address the Chafer issue before investing in a major lawn restoration. If you have chafer on your property you will need to manage this pest every year in order to keep your turf looking good.
Removal of soil from a site infested with chafer grubs is not recommended, as this will spread the pest to new locations, and won’t help to manage the pest in future years.
- Lightly rake over damaged turf areas to remove the thatch and debris.
- Top dress with 1-2 cm of compost or lawn topdressing soil mix.
- Reseed abundantly the damaged lawn areas.
- Lightly rake seeded area for good seed/soil contact.
- Water the seeded area frequently ensuring that it remains moist until 50% of the seeds have germinated.
Chafer Beetle treatment/maintenance calendar September- March
- Greatest bird and animal damage to turf. Besides letting the vertebrates eat as many grubs as possible, there are no additional methods of management to employ at this time of year.
- Make arrangements for chafer treatment on your turf by a licensed landscape company.
April - June
- Repair damaged turf areas and maintain established lawns.
- Raise mowing height to 6-9cm and leave clippings if possible.
- Pre-order nematodes from local garden centre by mid-May for application in late July.
- Obtain your Lawn Sprinkling Permit from the City.
- Apply nematodes as directed by your local garden centre. Water 2x/week, following watering restrictions.
August - September
- Water 2x/week, following watering restrictions, particularly on new turf.
- Continue with good turf management practices, and consider applying a slow release fertilizer.