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Diggin' It

The Rose Whisperer: Meet the beetles

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So do we just raise the white flag and watch our favorite summer plants fight a losing battle? In their homeland, native predators keep beetle numbers in check. Not so in America. Adult beetles have few enemies -- they aren’t tasty fare for birds although grackles, starlings, cardinals, redwing blackbirds, and robins do feed on grubs. (Ducks like them, too.)

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As a natural control, picking beetles by hand is safe but not very effective. Shake them into a pail of soapy water and they’ll eventually drown.

Don’t ever crush a beetle – as a dying insult it will release more pheromone and attract even more pests.

Milky spore is a bacterial disease harmless to humans and animals that kills grubs.Apply it to grassy areas of the yard, but it takes two to three years to become effective. Neem oil, insecticidal soaps, and sprays containing garlic have also been recommended. High-value plants can be protected with spun polyester covers such as Reemay.

Research done at the University of Kentucky shows that commercial traps may attract more beetles than are actually caught.  If you are determined to use traps, place them at least 30 yards away from plants you want to protect.

If you choose to bring out the heavy artillery and spray with insecticides, consult your local Agricultural Extension Service office for recommendations. Keep in mind that some kill beneficial insects and  must be used with care in areas frequented by children, pets, and wildlife.

I try to avoid the scorched earth theory of bug control and use a combination of spot pruning and insecticidal soap to limit the damage. I’ve also heard that beetles can be confused by the scents of garlic, mint, chives, catmint, basil, and onions. These companion plantings can’t hurt, and certainly might help in our struggle to bid sayonara to a determined enemy.

PSSST: Each year a new urban legend about beetle control pops up on the Internet. This year’s tip is to spritz individual beetles with plain old window cleaner. I haven’t tried it yet. Dr. Klein says that depending on the cleaner’s ingredients, it just might do a beetle in.

He also says the heavy rains this spring could mean bigger populations next year. So let me know what works for you so we can be well armed for the invasion of 2010.

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