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Lady beetles. What a genteel term.

By Al Cooke
Posted Wednesday, November 1, 2006

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Lady Beetles. What a genteel term.

I gather there is some disagreement and/or confusion about what kind of insect folks are dealing with. A reference on my shelf only lists the dozen most common lady beetles and they involve 10 different genera. There are others but these are the most common and they're all in the family, Cocinellidae. (The only local potato beetle I'm familiar with is the Colorado potato beetle in the family Chrysomelidae. And they are striped, not spotted). The references on my shelf were published before we came to know so well the multicolored Asian lady beetle, Harmonia axyridis that seems prone to plague local residents this time of year.

This particular Asian lady was introduced but not in NC. It was introduced in the southeast by USDA as early as 1916 but was first noted to have established populations in 1988 near New Orleans. According to USDA, there have also been accidental introductions. They seem unclear whether the establishment of the beetle in this country is from planned or accidental introductions. Doesn't matter now. All populations in NC have migrated here from neighboring states, mostly during the early 90s.

Exactly 2 years ago, November 1, 2004, I emailed the following information to my routine contacts via my E Letter.

"Working in the yard this weekend gave me opportunity to observe a number of things. Most of them I won’t bother you about. But I could tell that I will get calls later about the lady beetles (a.k.a lady bugs). Early in the day I noticed one. By late afternoon they were getting annoying as they flew into my face and even tried a bite to see if I were edible. By bedtime, there was even one there.

"And therein lies the problem. Lady beetles are considered beneficial insects. They are noted for consuming great numbers of other insects and mites that can be damaging to plants. So we’re generally glad to have them around. But we’re not so glad when one falls into our plates at suppertime. Or if they end up crawling in the baby’s bed. They are not so beneficial there.

"These guys (and gals) were first introduced from Asia into the US a couple of decades ago. For some years they seemed to remain fairly scarce. They showed up in NC in 1992, and seem to have been making a bit of a nuisance of themselves almost every year since. During spring and summer they are quite desirable to have feeding on aphids and mites in the garden. But by autumn they start seeking a place to spend the winter.

"In Asia that place was often the south facing side of a sunny rock face. In North Carolina, the sunny side of light colored buildings seems to suffice. Dark buildings, however, are not immune. Once they settle down, they tend to start looking for a nice crevice into which to crawl. On a rock wall, that crevice would protect them from the elements. Unfortunately on your house, that crevice probably leads to a wall void, more crevices, and eventually the interior living space.

"Although they may try a bite, they are relatively harmless indoors. They don’t feed on wood or carpet; they don’t reproduce. In fact many will die indoors. They may leave a stain if crushed. There are some concerns about potential allergic reactions to large numbers indoors.

"What can you do?

"1. Many people want to reach for “some spray.” Insecticides are of limited effectiveness. Repeated spraying indoors is costly, time consuming, and probably not healthy. (This is the same confined air space in which you live.) Aerosol “bombs” seldom get into the tiny places where many of them are resting.

"2. Exclusion. You probably can’t seal the house tightly enough to keep out 100% of them. But you may reduce the numbers by use of door sweeps and weather-stripping; sealing utility openings around wires and pipes; caulking cracks and crevices; and repairing or replacing window screens.

"3. Vacuuming. Be sure to empty the vacuum frequently as dead lady beetles smell bad. Dr. Susan Jones of Ohio State University has reported success by inserting a woman’s knee-high stocking into the hose end and securing it with a rubber band. Once the beetles are trapped, you can remove the stocking and secure them inside with the rubber band. If you desire, they can be kept in the refrigerator where some will survive until you release them into your garden in the spring. Or you can release them in some protected area now – under the porch, under the shed,…

"4. Blacklight traps. Probably more trouble than they’re worth unless you run a commercial kitchen or hospital. But those who are inclined can find guidelines at
http://www.ces.ncsu.edu/depts/ent/notes/Other/goodpest/harmoniatrap.pdf"

For more information, see
http://www.ces.ncsu.edu/depts/ent/notes/Other/goodpest/note107.html

Good luck.

Al Cooke is an Agriculture Extension Agent
Chatham County Center
North Carolina Cooperative Extension Service
N C State University
PO Box 279
Pittsboro, NC 27312
919.542.8202, FAX 919.542.8246

 
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