Japanese Beetle Control
Japanese beetles are eating the leaves of our newly planted apple trees. How can we control them? Thank you!
Kent County Michigan
Thank you for contacting MSUE's Ask an Expert.
Japanese are an annual frustration for all gardeners. You don't say how large your apple trees are or how many you have. If your trees are relatively small and the number of beetles is relatively small, the most effective and cheapest way to control Japanese beetles is to knock them off by hand early in the morning when they are not as active and drop them into a bucket containing a small amount of soapy water. Check your plants regularly as more beetles can fly into your garden. Japanese beetles are poor flyers, so if you place the bucket under them and tap the branch they are on, they will usually fall into the bucket and die rather than fly away.
Traps are not all that effective, because they tend to attract more beetles than they capture. If you decide to use a traps, place them several yards away from your apple trees.
If your trees are too large for hand-picking, sprays are commercially available which are safe for fruit trees. If you are interested in using a lower impact insecticide, try products containing neem. This insecticide deters Japanese beetle from feeding but is only effective on small or moderate numbers of Japanese beetle.
There are a variety of residual garden insecticides that work against these beetles, such as products containing bifenthrin, carbaryl, cyfluthrin, esfenvalerate, lambda‑cyhalothrin, or permethrin. Be sure to read the label on the insecticide carefully and see that the plants you wish to treat are on the label of the product you want to use. Repeat applications may be necessary, especially if large numbers are present. Another insecticide option is imidacloprid (one example is Bayer Advanced Tree and Shrub Insect Control), a type of systemic insecticide. This is not immediately effective as it takes at least two weeks before the insecticide is taken up by plants and kills the beetle.
The sooner you begin control the better. Once beetles begin skeletonizing leaves, the plant will put out a stress signal which calls in more beetles. They are partial to any plant in the rose family and that includes apple trees! Some years the beetles are more prevalent than other years.
Good luck with your new apple trees. If you have additional questions, please let us know. Thanks again for contacting Ask an Expert.