Masked Chafer

What it looks like

Masked chafers are tan beetles with a dark band across the head that looks like a mask. They fly at night in early to mid summer. Their larvae are white grubs: milky white, C-shaped, with a brown head.

Masked chafers have one life cycle a year. The young grubs feed near the surface in late summer, move deeper for the winter, and feed again in spring.

Damage

The grubs eat grass roots. The turf turns spongy, then brown, and can be rolled back like a carpet. Skunks, crows, and moles digging for grubs are often the first sign.

How nematodes help

The beneficial nematodes in Heteromask hunt grubs in the soil. Cornell rates H. bacteriophora (the nematode in Heteromask) as effective on masked chafer grubs, though one study found them harder to kill than Japanese beetle grubs. Treating young grubs gives the best results.

How to apply

Treat with Heteromask from March to June or August to September. Late summer and early fall is best, while the grubs are young and near the surface and the soil is warm. Scanmask also works.

Focus on areas of lawn that show damage and areas in full sun, plus the drip zones of shrubs and trees.

See How to apply for step-by-step directions, or use the calculator on the Heteromask Spray page to see how much you need.