Monday, February 18, 2013

The Asian Multicolored Lady Beetle: Invasion of the aliens

Asian multicolored lady beetle
Image: Iowa State University Entomology Image Gallery

Has your home been invaded by ladybugs (lady beetle) those cute beetles that smell vile when disturbed and that seem able to get through the tiniest of cracks? Read on to learn more about where they came from and what to do about them.

The Asian Multicolored Lady Beetle (Harmonia axyridis)came into this country through several routes and is both a good lady and a bad lady.  As early as 1916, this insect was introduced in California by the United States Department of Agriculture to help control insect pests in trees. Lady beetles also eat aphids. During the 1970s and 1980s, planned releases of tens of thousands of beetles continued on the East coast of the United States and Canada. There are also indications that the beetle entered the country through the ports of New Orleans and Seattle. 

In the fall, many of us find lots of the Multicolored Asian Lady Beetle congregating on our windows, under the shingles on our roofs, in our attics, and in other warm spots.  On warm, sunny days, they invade our homes, crunch under foot, drop into our food and generally make nuisances of themselves. When these little critters are disturbed, they defend themselves by exuding a yellow-orange body fluid that has a foul odor and can stain walls, drapes, carpeting, etc.   In addition, some individuals seem to be allergic to this body fluid and develop contact dermatitis or respiratory allergies.  

What to do?  

  • Seal all cracks, crevices and other possible points of entry.  
  • If they still get inside, use your vacuum cleaner to collect them. Cut a leg (about 10 inches from toe up) from a pair of panty hose and put it inside the vacuum cleaner hose; secure the panty hose leg with a rubber band and then vacuum.
  • Remove the panty hose, seal it, and dispose of it OR put the panty hose in a jar and store it in a cool place until spring when you can release the beetle so that they can help eat aphids.

The good and the bad beetle

When these lady beetles first appeared in Virginia in 1993, state agricultural specialists were not particularly concerned about them.  While they were definitely nuisances for many homeowners, they also ate aphids and other soft bodied insects that harmed trees. Since then, however, new field studies have shown that the adults feed on peaches, apples, raspberries, and grapes, especially when they have been slightly damaged.  Perhaps even more importantly, they have been termed a devastating contaminant in wine production throughout the Eastern and Midwestern United States.  The beetles are often present on grapes when they are harvested, and are difficult to remove.  The beetles get crushed with the grapes and contribute their distinctive foul odor to the wine.

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