The Q&A Archives: Japenese beetles

Question: What can i do to control the japanese beetles? what kind of insecticides?? do i need a bag?? give me some suggestions how to get them off my Roses and keep them off. Also when do i cut them back?? they are Knock -out Roses.Do i cut the parts already damaged by the beetles ? thank You

Answer: Japanese beetles are a difficult pest to control. Your best bet is a two-prong approach: one to deal with the larvae, one to deal with the adults. Japanese beetle grubs are best controlled by spraying beneficial nematodes on the lawn and garden area. These microscopic worm-like creatures attack only the grubs in the soil and not plants, animals or humans. Spray them in spring when the temperatures are above 55F. You can buy the beneficial nematodes from Gardeners Supply, 128 Intervale Rd., Burlington, VT 05401 800-863-1700 For adult beetles, I'd try a new product called whole neem oil. This is different than standard Bioneem in that it is a stronger concentration of this organic spray. It's available from Greenlight Co., Box 17985, San Antonio, TX 78217, 210-494-3481. Diazinon and Sevin sprays will take down the adults. Be sure to follow the label directions EXACTLY and use care when spraying ANY poisons. Rotenone and Pyrethrum sprays are also effective Ortho's Rose Care Insecticide is also labeled for control of beetles. It's available from Home Depot.

You can prune your Knock Out roses back in February when they are dormant. You can prune away the beetle damaged parts now.

Best wishes with your landscape!

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