Japanese Beetle

What it looks like

Japanese beetles are easy to identify by their metallic green bodies and copper wing covers, and are about ½ inch long. The larvae, called grubs, are milky white with a distinct raster pattern (the pattern of hairs on the underside of the tail end).

Japanese beetles have one life cycle per year. Adult beetles lay eggs during the summer, which hatch about 2 weeks later. In late summer and early fall the young grubs feed on plant roots before spending the winter in the soil. The grubs wake up in early spring and keep feeding before changing into pupae, and then adults.

Damage

Adult Japanese beetles feed on the leaves of hundreds of kinds of plants, often in groups, leaving only the veins behind like a skeleton. The grubs feed on the roots of grass and garden plants, causing brown spots and dying grass that pulls up easily, or even rolls back like a carpet.

How nematodes help

The beneficial nematodes in BioLogic's products hunt down and kill grubs in the soil. Killing the beetles as grubs stops the life cycle, so new adults don't emerge.

How to apply

Heteromask is our preferred product for white grubs, including Japanese beetle grubs, but Scanmask also works. Concentrate on areas of the lawn that show damage.

Treating in late summer or early fall is ideal, when the young grubs are small and most vulnerable. There is also usually a short window in early spring, before the grubs get too big and pupate. One application typically lasts about a year, and often longer. Treat again when you notice Japanese beetles or grub damage coming back.

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