I recently had the "pleasure" of being visited by some Chinese rose beetles. Well not me personally since I'm neither green enough nor sit still long enough, but my poor apple trees. One week I happened to give the young apple saplings a glance and was dismayed to see their foliage peppered with holes. With not any leaves extra to spare, I felt that I had to do something ASAP to rectify the situation.
Plan of attack :
...Go out one hour after sunset armed with a flashlight. Inspect each leaf, especially the bottom, for Chinese rose beetles. Pick off each one and squish it. (For the squeamish, the beetle could be drooped into a jar of soapy water.)
...After eliminating beetles for three nights and still seeing no reduction in their numbers, mix up a spray bottle of Sevin. Spray tops and bottoms of all leaves. Make a tripod to hold an umbrella over each sapling so that the rain does not wash the Sevin off.
...Three days later, with the beetle population still high, bring out the big guns....Bayers insecticide, the controversial imidacloprid. Spray the bottoms of all leaves.
Once the beetles were pretty much gone, I backed off to spraying the undersides of the leaves once a week with Sevin. Within a couple weeks new leaves were emerging. Success!
Most likely I could have stuck with just the Sevin and done ok. I seldom resort to Bayers insecticide.....but frankly I don't apologize for using it at times. In my entire lifetime I will be using less total than one commercial farmer uses in just five minutes. Plus I do not spray it near flowers that attract bees. So if you have a bee in your bonnet about pesticide use go talk to Green Giant, DelMonte, ConAgra, etc.
Now that I know that apples are a preferred target of the Chinese rose beetle, I plan to do something more benign to control them. I've been told that they are repelled by bright light. That really won't help me for two reasons.....one, the apples are located a good distance from my home and thus the electrical source, and two, being on a small solar system I am not willing to run light bulbs all night long. Running a generator beside the apple trees is not acceptable to either me nor my neighbors. Besides, it's been raining here every night so any electrical set up would have to be sheltered from the wet, be it wiring, generator, battery, etc. So this option is out.
Next, these beetles are attracted to low light, such as one of those solar lights people stick along their driveways or walking paths. Thus I could fashion a trap where the beetles are attracted to the light, hit it and are knocked into a bowl of soapy water below the light. This is one idea I plan to pursue.
Next, I could get in the habit of checking for and killing any beetles I see on the apple leaves right after dusk. That way I could nip the problem in the bud before the beetles get well established. And if needed, could spray an insecticide if the soap bowl doesn't work well enough.
I will be monitoring my Chinese rose beetle problem and keep you informed how things develop.