Login / RegisterHow to stop the European chafer beetle from destroying your lawn
Is this “monster” living in your backyard? The odds are high if you notice crows or skunks digging up the grass. The European chafer beetle is a new pest in B.C. and is spreading fast in Vancouver, Burnaby, New Westminster, Coquitlam, North Delta, and Richmond.
European chafer completes its life cycle in one year. Adults emerge in late May to early July, fly to nearby trees to mate, and each female deposits about 50 eggs below the soil, which hatch in mid July. The larvae (grubs) have C-shaped bodies and feed on turf roots all fall. During winter they dig down for periods of freezing conditions, and resume feeding in spring until April when they become pupae. Adults are tan colored and do not cause any damage.
Homeowners should mow at five to eight centimetres high during adult activity period, as egg-laying female beetles do not prefer taller turf. To inspect your lawn, cut several test sections 12 inches square and look for white grubs. If you count five or more grubs, control is warranted. Healthy, well-maintained turf can withstand low levels of grub feeding. Although digging by birds, skunks, and raccoons damages turf, it also helps decrease the pest populations.
Bio-pesticides containing “cruiser” nematodes are available for grub control, which work best if applied from late July until September when grubs are relatively small. Research shows that some naturally occurring soil organisms also infect grubs and make them sick, reducing their impact.
Rana Sarfraz is a researcher at UBC who is studying the disease susceptibility of European chafers and is hoping to identify a more effective microbial product for their control.
Thanks for your comment. Glad that you find it helpful.
1. The recommendation of treating the lawns with nematodes in late July to Sept is based on the life history of the pest. Chafer grubs have larval three stages. They are most vulnerable/susceptible to nematodes when they are small (1st and 2nd stage) and actively feeding, which is late July to Sept (remember, the eggs hatch in July), but homeowners are usually unaware of the problem during these months.
Unfortunately the chafer problem is generally discovered in fall (Oct/Nov) when birds and small mammals begin decimating the lawns– by now the grubs reach the 3rd-stage, stop feeding and retreat to their winter cells (diapause)– therefore they are generally inaccessible or less vulnerable to nematodes. Next March - May, the 3rd-stage grubs from the previous fall, crawl back to grassroots near the soil surface to resume feeding and then pupate in June (again, these 3rd stage grubs and pupae are not susceptible to nematodes). Homeowners, therefore, have only a narrow window of time (Jul to Sept) for nematode applications.
Note: chemical insecticides can still be applied in Aug-Sept or Apr-Jun. Follow the label carefully.
2. Adult beetles fly to nearby trees, mate there, fly back to the soil surface, and lay eggs in the SOIL. They don’t lay eggs on trees. Sorry, I should have written this article in detail, but did not do so thinking of space limitation.