Paul Zimmerman, contributor
Every rose gardener has come to hate Japanese Beetles (Popillia japonica). Every summer they emerge from the ground and begin their voracious chomp through the garden. While they love all kinds of plants, they particularly seem to love roses. It breaks any rose grower’s heart to walk out and see their shiny bodies encompassing a just opened blossom. While they are found mostly in the Eastern United States, there is evidence they are moving further west.
The commonly recommended chemical treatment is Sevin, either in liquid or powder form. I’m not keen on this, as I feel Sevin can also harm to insects we want to keep around. Personally I advise against it. Liquid soaps won’t work because Japanese Beetles are hard-bodied insects as opposed to aphids, mites and thrips that are soft-bodied.
I’ve talked in the past about letting nature achieve a balance between “good” and “bad’ insects in the garden. The idea being you need some of the “bad” guys around because they are a food source for the “good” guys.
Here’s the problem. Japanese Beetles are not native to our shores, so therefore they have no widespread natural predator in the United States. In their native Japan, this is not an issue because they do have natural predators. I’ve heard ducks love them but I’m not sure I want to see a bunch of ducks perched on my roses!
Japanese Beetle Traps don’t really work because they tend to lure in more beetles they can handle. Picking them off by hand, drowning them in a jar and getting them off the property, while satisfactory from a revenge standpoint, is laborious at best. Simply shaking them off and stomping on them attracts more because when killed, the female emits a pheromone that attracts males. Hardly the desired result.
So, is there a natural alternative? Thankfully, the answer is yes. Double thanks because you can make it yourself! It’s simply a spray made from cedar oil! Preferably Eastern Red Cedar. The principal is the same one used when storing sweaters in a cedar chest to keep moths away. When sprayed on the roses it keeps the beetles away and they fly off to another garden. I know this for a fact because I’ve tried it and boy did it work!
You can buy it from various on-line sites but recently I found a recipe for it. Simply take a few red cedar planks say a foot long each and put them in a one or two gallon bucket. Pour hot water over it and let it steep like tea for 24 hours. Cut the planks in half if needed, but make sure they are totally immersed in the hot water.
Pour the liquid (don’t dilute it) into the sprayer of your choice and spray the roses and the beetles. You may have to play around with how much cedar wood you use to get the right strength. When you have it right the beetles will either fly away or drop off almost instantly.
I’ve been asked if this would work with cedar shavings and in all honesty I don’t know. I have not tried it but if you want to give it a go let me know how it works! I’ve also seen red cedar oil for sale by itself and that diluted in water might also work.
None of us like Japanese Beetles but the chemical alternatives can sometimes do more harm than good. Thankfully a natural control is here and rapidly gaining traction.