Answer: Rose chafers are related to Japanese beetles, and their life cycle and control measures are similar. Although their preferred foods are rose and peony blossoms, they can also be pests on apple, crabapple, grape, cherry, strawberry, raspberry, hydrangea, hollyhock, and many other ornamental plants and vegetables.
There are a number of different controls for rose chafers. You can hand pick them: As soon as you see the 1/2-inch-long, light tan, long legged adult beetles, usually the end of June or early July, go out to your rose patch daily to pick the insects off the plants and drown them in a can of water. The adults are only around for a few weeks, so if you are diligent, handpicking works.
For those without the time or temperament for handpicking, you can spray insecticidal soap. Avoid spraying during the hottest time of the day and don't spray directly on blossoms, as doing so may cause blossoms to deform and can harm pollinators.
Beneficial nematodes will also reduce the population of rose chafer larvae in the soil without harming earthworms or plants. Spray the nematodes on your lawn in spring or fall (when larvae are in the upper layer of the soil). Timing the spray is important. The nematodes are effective only against the larval stage of the chafer. Spraying when you see the beetles is useless.
Q&A Library Searching Tips