Green June Beetles and Japanese Beetles
Green June beetles and Japanese Beetles are similar in appearance and are often confused with one another, but Japanese beetles are much more destructive. Green June Beetles are large (about 1 inch long,) are velvety green on top, and shiny green underside. While they don’t cause any serious problems for your plants, they can be annoying since they fly into the sides of buildings and even people frequently. They are generally only active in June and July. Their grubs feed on decaying organic matter. A blanket pesticide, such as one containing Bifenthrin, will need to be sprayed throughout the lawn and shrub area where the adults fly for control.
Japanese Beetles are newer to our area but are becoming more destructive as they get established. They are much smaller than Green June Beetles, about 1/3 to 1/2 of an inch. While they also have green highlights, they have a reddish cast to their shells and five small white spots down their sides. The white spots are tufts of hair and the easiest way to ID them. The adults are usually present from July through August and feed on roses, fruit trees, and multiple other plants. They often feed in groups, quickly defoliating desirable plants.
Females then lay eggs that hatch into white grubs. Grubs can seriously damage lawns, usually in June, before they emerge as adults in July.
They can be controlled in June with Bioadvanced’s “24 Hour Grub Killer.” The adults can be controlled by hand-picking them off plants early in the morning or with a product containing permethrin or bifenthrin.