They’re Back! My old foes. Their nasty iridescent purple bodies are mating wildly in my crabapple and linden trees. They are covering my (formerly) gorgeous rugosa rose bush, munching down my dahlias, and (blissfully) drowning in my outdoor water feature– a nice healthy snack for Penelope, our female betta fish, who resides within the water feature.
I know that there are plants that they love- like the Linden, and the best advice is probably not to plant them- and any good Google search will give you a great list of the usual suspects: rose family (which I think includes crabs and cherries), lindens, dahlias, hollyhocks, hibiscus, daylilies, coneflowers. There are hundreds more. When you are planning your garden, don’t plant these plants if you have a japanese beetle problem. Last year, I pulled out my hibiscus, because they attacked it so badly and I was tired of never being able to see it bloom.
I have a theory that I have never heard elsewhere and would love to see someone get their PhD in– in my experience, the beetles prefer things that match them. Purple Palace Heuchera, Crabapple “Profusion”, Sand Cherry, Dark Leaved Dahlias. Maybe it’s a camouflage thing, but they clearly prefer certain dahlias and will not bother others. My red pom-pom dahlia has no takers, even though I plant it in the “Japanese Beetle Garden” (where all of the unfortunates that I didn’t have the heart to kill– plants that is– now reside.)
My other theory is that they only like these colors if they get sunshine. My japanese maple– a usual favorite of these nasty insects, and a beautiful purple color– has no takers either, because it is sitting in the shadiest part of my garden.
While you often hear laundry lists of things not to plant to avoid attracting the beetles, here is a list of things that are not bothered by the beetles– which is far more useful, in my humble opinion. Hydrangeas. They’ll sit on them, but won’t eat them. Erynginum. Russian Sage and other sages. Common Orange Daylily. Queen Anne’s Lace. Liatris. Delphinums. Sedums (unless they are really desperate), Heather, Magnolias.
The only real way to kill Japanese beetles, based on my experience, is to drown them. An overnight in a soapy bucket of water will do the trick. I tried milky spore powder on my lawn and gardens when I first moved in and have not noticed any result. If the entire neighborhood treated its yards with Milky Spore, maybe we’d see some change.
Of course, you could use chemicals– and there is a systemic granular tree chemical that you spread around the base of the tree, which poisons the leaves. I use this on my linden tree only, because I would like other animals to eat the fruit on my other trees. I find that encouraging birds helps control the population better than chemicals, so have to make sure that my bird feeders are topped up.
Those japanese beetle traps are great for attracting beetles– so encourage those neighbors far away from you to put some up- hopefully it will distract the beetles from your garden.
I believe that the real culprit behind the many japanese beetles in my neighborhood and elsewhere are overfed and overwatered lawns, the lawns are what the beetles really need to allow the grubs to grow to adulthood. Grubs feed on grass roots and will destroy the grass- necessitating more water and fertilizer and chemicals to keep the lawn looking green. The day they hatched on a local golf course, my husband and I were out playing– it was insane to see thousands and thousands of them emerge from the ground.
A final note– let me be clear that Japanese Beetles are not Asian Lady Beetles, the ones that come in your house in the winter and look like ladybugs. If you don’t know the difference, you probably don’t have Japanese Beetles– they are disgusting and distructive to the garden, whereas the Asian Lady Beetle is largely just annoying when it comes inside.
My best advice on Japanese Beetles is detente. This is the time of year where summer is usually the hottest- so better to cut a large bouquet of hydrangeas, sit on the porch and drink a glass of lemonade than to try to drown the 300,000 or more Japanese Beetles currently infesting my garden.