Controlling Japanese beetles
Japanese beetle adults are hatching and flying around in my garden. It's time to go on the offensive. The c-shaped white larvae that have been living in the lawn for the past months have finished pupating and the result is the coppery black, hard shelled adult beetles. These beetles love roses, grapes, raspberries, basil, hollyhocks, evening primrose, and a number of other plants. They tend to feed in groups almost as if when one finds a great plant it signals all its friends to come join in. Their whole purpose in life is to eat and mate, so they like to hang out together.
Here are some control ideas to try.
Handpicking. Go out in the morning while the beetles are still sluggish and handpick them. Drop the adult beetles into a pail of soapy water. Another method is to place a sheet under the bush or plant where many beetles are congregated, and shake the plant. The beetles will naturally roll and drop, falling onto the sheet. Spill them into the pail of soapy water.
You can also hire local kids and pay them a penny a beetle to handpick them. The key is to do it everyday through July to reduce the population.
Barriers. Use barriers such as floating row covers on prized plants. This white, cheesecloth-like material let's sun, air, and water in, but blocks out the beetles. Although unsightly, it can save a plant from being defoliated by beetles.
Sprays. There are safe sprays on the market that can control Japanese beetles, but you'll have to spray often since these beetles may fly in from elsewhere. Neem oil and pyrethrum are probably the best products to use.
Traps. Japanese beetle traps are a 2-edged sword. They do lure beetles in with their scent, but often the beetles will stop and munch on your plants instead of dropping into the trap. The best way to use the traps is to have the whole neighborhood trap beetles so you aren't the only one luring the beetles to your yard.
Long term control. For long term control spread milky spore disease or beneficial nematodes on your lawn area around the most heavy infected plants. Japanese beetles tend to lay their eggs in the lawn close to these plants. Spraying in early summer and fall reduces the number of larvae and the future number of adults. I did this once at my old house where I was growing lots of roses and within 2 years I significantly reduced the beetle population.
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