How to Treat for Japanese Beetles

You can treat for Japanese beetles at both the grub and adult stages.

Japanese beetles can appear as garden pests both in their adult stage as green beetles and in their immature stage as white grubs. The adult Japanese beetles eat the foliage of many types of flowers, eating between the tissue. Evidence of adult beetle invasion includes a lacy pattern of holes in the leaves. The grubs can also do damage, as they eat the roots of grasses. A lawn with dying patches may be the work of Japanese beetle grubs.

Things You'll Need

• Bucket of soapy water
• Insecticide containing a form of pyrethroids, or carbaryl or acephate
• Insecticide containing imidacloprid or halofenozide

Instructions

1. Spray the grubs before they can mature, applying the spray in June and July. Apply insecticide containing imidacloprid or halofenozide. Follow the manufacturer's label to determine pounds of active ingredient per acre needed. Water the sprayed area after applying insecticide.

2. Pick off and remove adult beetle scouts before others arrive in your garden. Remove the beetles from plants and place them in a bucket of soapy water to exterminate them.

3. Spray adult beetles, if large swarms appear, using an insecticide containing either a form of pyrethroids, or carbaryl or acephate. Apply every five to ten days, following the instructions on the manufacturer's label to determine amount and application technique.

Tips & Warnings

• Plant flowers that are not attractive to Japanese beetles to prevent the problem. Some common flowers include: begonias, carnations, columbines, daisies, and hydrangeas.

• Store all insecticide out of reach of young children and pets.

References

• Ohio State University: Control of Japanese Beetle Adults and Grubs in Home Lawns