Known to feed on corn, roses, grapes, as well as 250 other plants, the Japanese beetle is widely considered a nuisance in most gardens. There are several ways to control Japanese beetles in your yard.
Choose your plants carefully. If you live in a place where Japanese beetles are a problem, choose plants that are unaffected by them. This is the easiest way to control the beetles.
Watch your plants. Particularly, watch smartweed, linden trees, or other favorites of Japanese beetles. Immediately remove Japanese beetles as they show up, and discard the foliage that has been damaged. By doing this you will eliminate signs that would attract beetles.
Cover certain plants. Small plants should be covered with netting that is fine (less than one-quarter inch) during the beetles’ peak activity time. Ensure that there are no openings in the net that would enable the beetles to get through.
Use insecticides. There are several insecticides out there that will defend lawns from Japanese beetles. Some insecticides include: Bacillus papillae (Doom, Milky Spore,) carbaryl (Sevin), chlorantraniliprole (Acelepryn), and clothianidin (Arena). Always be sure to follow manufacturers’ directions.
Use Trap Plants. One option is to use trap plants (unwanted plants such as smartweed) to distract the beetles from more desirable plants. This could be problematic, however, in that it could potentially bring more Japanese beetles into the garden.
To prevent Japanese beetles, it’s best to use products containing either imidacloprid or halofenozide in late June to early August before the eggs hatch. After the eggs hatch in August, use curative grub treatments. The following methods don’t work when attempting to control Japanese beetles:
Japanese beetle traps. While they trap numerous beetles, some of them were drawn to the area specifically by the trap and may cause more damage to the plants in the area.
Grub insecticides. While insecticides can control younger Japanese beetles and prevent lawn damage, they don’t necessarily control adult beetles, who can fly distances up to two miles to feed.
Home remedies. Smashed-up beetle spray and other home remedies don’t generally work and should be avoided.