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Archive for Thursday, October 4, 2012

Garden Calendar: Insects, spiders coming in for winter

October 4, 2012

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Boxelder bugs, red-shoulder bugs, roly polies and wolf spiders are this fall’s popular invaders.

These little creatures are just looking for shelter from the rapidly approaching winter — and, with the exception of brown recluse spiders, are not dangerous to humans — but they can be a real nuisance when they try to cohabitate with us.

To keep insects and spiders out of your living areas, seal all the cracks and crevices on the outside of your home, replace damaged screens and ensure that doors and windows seal tightly. I know this can be a monumental task, especially in an old home, but it is the truly the most important step toward excluding insects from a home’s interior.

For the bugs that do slip in, physical removal is the first option. Hand-pick and move them back outdoors or vacuum the insects up. If vacuuming insects, you may wish to remove the bag and dispose of it, as some insects can chew their way out. Multicolored Asian lady beetles, which are not a big problem this year but have been in the past, are notorious vacuum bag chewers.

Spider relocation is another issue, as most people are averse to hand-picking even the nicest of spiders. Drop a cup or other container over the top of a spider and slide a piece of thin cardboard or heavy paper underneath to contain the spider. Then pick up the paper and cup together and flip them over. The spider can be taken back outside or disposed of however you see fit.

When stronger tactics are needed, control depends on the species. Here are recommendations for the pests our horticulture hotline is getting the most calls about.

Boxelder bugs and red-shoulder bugs

Red-shoulder bugs are related to boxelder bugs, and they look and act similar. They are usually black with reddish-orange tinges on their upper edges of their bodies.

When exclusion and physical removal are ineffective at eradicating boxelder and red-shoulder bugs from a home, an outdoor population may be to blame.

A stream of water directed at the insects through a high pressure nozzle is effective at killing boxelder and red-shoulder bugs while they are resting.

Although cleaning up around the exterior of the home can help at controlling these bugs, removal of boxelder trees that attract the insects is sometimes impractical.

Because the populations cycle from year to year, they may be something that can simply be tolerated when populations are high.

If insecticides are warranted, read and follow all label directions. Some insecticides limit where the product can be used — typically to trees or to the perimeter of a home.

Roly polies (pillbugs and sowbugs)

Pillbugs and sowbugs feed on decaying organic matter, so eradicating them from a home means destroying feeding and breeding sites. House plants could be the culprit, but leaves, compost, boards and mulch near the perimeter of the home can also exacerbate the problem. Control of outside populations is critical to eliminate indoor populations.

If pillbugs and sowbugs continue to be a problem after cleaning inside and outside the home, an insecticide could be used. There are several hundred products available that are effective on pillbugs and sowbugs.

Always check the label to make sure the product has the insect you want to kill listed on it, and read and follow label instructions. Some insecticides will only kill adults, while others have some residual activity.

Wolf spiders

Cleanliness is key. Vacuum under furniture and in dark corners where wolf spiders like to hide. Also, since wolf spiders feed on other insects, control the other insects first to deplete the spiders’ food source.

Clean up debris around the outside of the home where wolf spiders might live so that they will hopefully move farther out into the yard.

There are many pesticides labeled for wolf spiders. An aerosol spray can be used for quick knockdown (in place of relocating with a cup). Residual sprays can be used to treat cracks and crevices, door trim, the undersides of furniture, crawl spaces and other hiding spots. Always read and follow label instructions.

Brown recluse spiders

Cleaning is again important, but brown recluse are very efficient at finding places to hide. Use glue traps behind furniture, along baseboards and in closets and cabinets. Glue traps are sometimes called sticky traps, and there are many brands available. If you have children or pets, try to put the traps where they inaccessible. Pulling a glue trap off a dog’s nose can be quite a chore.

Aerosol sprays labeled for brown recluse are only effective at killing the spiders when you see them. An insecticidal dust will provide the best residual activity against brown recluse if a pesticide is necessary.

— Jennifer Smith is the Horticulture Extension Agent for K-State Research and Extension in Douglas County. Contact her or an Extension Master Gardener with your gardening questions at 843-7058 or dgemg@sunflower.com.

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