This summer, a couple of homeowners recently called about swarms of Japanese beetles. Japanese beetles have been a thorn in gardeners’ sides for many years and it seems as if they are again returning as a problem in Rowan County. These pests damage roses, crape myrtles and other flowering plants including vegetables. These beetles have a wide host range-feeding on over 275 different types of trees, shrubs and vegetable plants. One of the most recognizable insects, the Japanese beetle is oval, just under 1/2 inch long with a metallic green body and copper-colored wings. The insect plays dead when disturbed for a few seconds only to resume normal activity foraging for food.

Insecticides containing Sevin can be applied as a dust or a liquid for immediate control, however, Sevin-based insecticides are highly discouraged due to toxicity to pollinators, especially honeybees. Japanese beetle traps can be implemented as an alternative control method implementing a pheromone (sex attractant) luring the insect into the trap. Research has shown that Japanese beetles are attracted to bright colors, especially “John Deere” yellow. Unfortunately, these traps which are bright yellow, attract more beetles to the very plants you are trying to protect.

Homeowners can apply soil insecticides in the spring to control the grubs. Bacillus thuringiensis (Bt) is a natural occurring bacterial insecticide that has been developed as a microbial insecticide for controlling grubs.

Hand picking beetles is another method of control if the beetle population is not too great. Fortunately, most damaged plants recover soon after the initial invasion. Go to https://lee.ces.ncsu.edu/2023/07/japanese-beetles-facing-the-onslaught/  for more detailed information.

Darrell Blackwelder is the retired horticulture agent with the North Carolina Cooperative Extension Service in Rowan County. Contact him at deblackw@ncsu.edu.