Dealing with Japanese beetles

The pest I’m hearing about most from west Michigan gardeners this year is Japanese beetles. These pesky little copper-colored beetles especially love roses and apple trees—both of which we have on our property, so I have been especially interested in monitoring them for activity.

Their telltale sign is leaving “skeletonized” leaves while leaving the veins intact. Unfortunately Japanese beetles are not real picky eaters and will attack almost any flower, shrub, tree, or vegetable plant. My first encounter with the Japanese beetles this year occurred when they showed up on my pole beans; they’ve also enjoyed some of our cucumber plants.

So how do we get rid of them without nasty pesticides?

First spray your plants with Neem oil. The benefit of Neem oil is it is derived from an evergreen tree and is safe for use around humans, animals, earthworms, lady bugs, and other beneficial insects. Neem oil also protects your plants from a variety of other insects including caterpillars, cabbage worms, mealy bugs, mites and whiteflies, just to name a few. Neem oil can also help with powdery mildew. This is an item I wouldn’t want to start the year without because there is a good chance I will need it at some point during gardening season!

Second, Japanese beetles are slow and not all that alert. This makes them easy to catch. Fill a bucket or jar half way with water and a squirt of dish soap. Catch the beetles with your gloved hands and place them in the bucket. They cannot escape from the soapy water. The best time to catch them is early in the morning when they are the least alert although you should have no problem catching them anytime during the day. Also leave the bucket of dead beetles in the garden as a deterrent.  Japanese beetles are largely moved by scents and the smell will deter additional beetles.

Finally, grubs are the larval stage of the Japanese beetle and the presence of the beetles in your garden or on your roses may mean you or your neighbor have a grub issue. Japanese beetles will travel a mile for a good meal, but if they are in your garden and you didn’t have grubs this spring you may have them next spring. Grubs can be treated organically with milky spores, but the milky spores take a year to effectively establish themselves in your soil. I know we will be applying them this fall to get a jump on any problems with grubs in the future.

Now that I’ve given you some good ways to rid your yard of Japanese beetles, here’s what I’d avoid: Japanese beetle traps. Studies have found they attract more beetles than they actually catch.

So is there a way to prevent these pests from invading your garden? Well, theoretically, natural repellants for Japanese beetles include chives, garlic, catnip and tansy, but to be honest, I have not found these to be very effective. Directly below my pole beans are my chives, so I’m not convinced planting those things actually works as a deterrent.
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So while you may not get rid of the all the Japanese beetles in your yard, you can definitely control their population so they will not have an impact on your harvest.