Monday, October 19, 2015

Asian Lady Bugs: Unwelcome Halloween Decorations

Asian lady bettleWhat’s round to oval-shaped, mostly orange, and is a common sight leading up to Halloween? Everyone knows the answer to that: Harmonia axyridis, obviously. Better known as the multicolored Asian lady beetle, this insect, while beneficial to gardens, is no treat when it masses by the hundreds on, and inside, homes in the fall.

Lady beetles, or lady bugs, are the darlings of small children everywhere. There are a number of native lady beetle species, which tend to be more reddish than orange, and they aren’t known to be nuisances in homes. Multicolored Asian lady beetles, however, are not as polite.

First brought to the U.S. in 1916 to control pests on pecan trees and other crops, the multicolored Asian lady beetle didn’t turn into an ogre until the mid-1990s. Actually there’s evidence to suggest that the current population is a new strain accidentally released at the Port of New Orleans around 1993. Whatever their origin, they’re back in season now along with corn shocks and Jack-o’-lanterns.

Lady beetles don’t carry disease, damage structures, suck blood or sting, and they eat harmful garden pests. However, they stain surfaces, give off a foul odor when disturbed and will even pinch one’s skin on occasion. It’s their sheer numbers, though, swarming an exterior wall, huddling in a corner of the garage or coating the inside of a picture window, which unnerve and irritate so many people.

Managing lady beetles, it turns out, will cut your heating bill. They’re looking for someplace warm to spend the winter and if a draft can get in, they can too. Caulk around windows, vents and places where cable or other utilities come through the wall. Be sure to seal between the foundation and sill. Ensure that door sweeps and thresholds are tight, and check for cracked seals around garage doors. Install screens on attic vents and inspect all window screens.

If the beetles are already indoors, don’t swat or crush them or they’ll release a smelly and staining yellow defense fluid from their joints (creepy, I know). For a variety of reasons including the lady bugs’ habit of seeking inaccessible areas, indoor pesticide use is strongly discouraged. Instead, use a broom and dustpan or a vacuum cleaner. Try using a knee-high nylon stocking inserted into the hose and secured with a rubber band as a reusable “mini-bag.” Just remember to empty it as soon as the vacuum is turned off. You can also make a black light trap; instructions can be found online.

This fall, researchers will be decorating giant pumpkins to look like multicolored Asian lady beetles in hopes of frightening the actual pests away. We just hope it doesn’t attract a mate of similar size. If you see a 100-pound multicolored Asian lady beetle on Halloween, please call the Cooperative Extension. Definitely don’t swat it.

Photo courtesy Wikimedia user spacebirdy.

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Paul Hetzler has been an ISA Certified Arborist since 1996. His work has appeared in the medical journal The Lancet, as well as Highlights for Children Magazine.You can read more of his work at or by picking up a copy of his book Shady Characters: Plant Vampires, Caterpillar Soup, Leprechaun Trees and Other Hilarities of the Natural World

2 Responses

  1. John Omohundro says:

    As always: informative, funny, timely. The idea about the knee high stocking is great. I’ve actually started to make a game of vacuuming up the fall cluster flies. I’ll keep a chart of my kill count on the refrigerator. Sick, I know, but I didn’t start this.

  2. Lisa says:

    I agree, as always: informative, funny, timely! John’s chart of the cluster fly kill count made me laugh. When my husband and I go canoeing during the summer we take electric fly swatters and have deer fly hunting contests. He with the most flies @the end of the trip wins. Sick, too, but it can help keep your mind off the annoyances these small creatures create.

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