Halting their activities. These 3/8-inch-long iridescent beetles, which feed on many kinds of buds, leaves, flowers, and fruit, are especially fond of corn and roses.
They overwinter as Enlarged grubs in soil 8 to 10 inches below the surface. In spring they move nearer the surface to feed on grass roots; in early summer they emerge as adults.
Battle grubs by applying milky spore disease (a preparation sold at garden supply stores) on a mown lawn; follow label instructions. The disease is self-perpetuating and effectively controls grubs for several years.
Shake beetles off plants into a pail of soapy water, or snare them with synthetic bait in Japanese beetle traps bought at a garden center. Effective sprays are carbaryl, malathion, or methoxychlor.