Home invasion of stink and lady bugs?
As temperatures go down with fall and the coming of winter, many in the High Country will experience a home invasion of bugs. This is especially true for two insects: the scary-looking stink bug and the small, spotted lady beetle (often called a ladybug). Each of these bugs is not native to our area but rather from Asia. In the case of the stink bug, which can be damaging to plants, their presence is accidental, while the beneficial lady beetle was initially brought into the U.S. on purpose. Regardless of their origin, many people find these insects a nuisance during the winter months as the bugs make themselves at home indoors. This behavior is the result of their life histories.
The brown marmorated stink bug, Halyomorpha haly, is often referred to as BMSB. It was first discovered in Pennsylvania and eventually found its way to the North Carolina Piedmont and mountains. Like many stink bugs, this insect sucks plant liquids for food and can damage garden and agricultural plants. The common name “stink bug” comes from the foul smell they may emit when handled or crushed. When the weather begins to get colder in fall, the BMSB finds a sheltered place to overwinter, such as holes in trees, or better yet your home. The number you have inside depends on how many ways the bugs can find to get in. Unlike us, insects don’t have a way to keep their bodies warm, so they are greatly affected by the temperature around them. In order to survive the cold outside temperatures a warm home is a very tempting place to reside. Stink bugs can be found on your ceilings, lamps, walls, and kitchen counters, to name a few places. To make matters worse, though the bugs are inactive if overwintering outside, the warmth of a home allows them to stay active essentially all the time. Stink bugs do not bite, and at this stage of their lives are not interested in eating; their big threat is the nuisance they create. When spring comes, they’ll start to disappear as they make their way back outside to find mates and reproduce.
Brown Marmorated stink bug
Susan Ellis, Bugwood.org
The multicolored Asian lady beetle, Harmonia axyridis, is a different story since these insects are quite beneficial to your garden and neighboring plants. Lady beetles feed on other insects (especially aphids) that are damaging to plants so are really gardeners’ helpers. This is the reason the insect was purposely brought into the western United States many years ago, though many probably found their way to the US accidentally on the plants found on ships. Like the stink bug, the lady beetle seeks shelter for the winter to get out of the cold- your home is very inviting. One thing to notice about these lady beetles is that they are strongly attracted to light, so you’ll especially find them on windowsills and skylights. They can bite (not much of one- they’re small!), and put out a nasty smelling chemical from their legs to fend off things trying to eat them, making for an unpleasant encounter if you handle them. The insect also puts out chemicals that attract other beetles so it can be found in large groups inside the home. With the coming of spring the Asian lady beetle heads back outside in search of insects to eat.
Multicolored Asian lady beetle
Brantlee Spakes Richter, University of Florida, Bugwood.org
So what does one do about these bug home invasions? Most people of course don’t want either of these bugs in their home over winter and are unwilling to wait for their exit in spring. The best strategy for keeping them out is to seal any openings around windows and doors so they cannot get in. Once inside the easiest way to remove them is to vacuum up the bugs and discard the bag. Be aware that since each of these insects can emit a foul smell the bag may wreak! Other ways to deal with them include, for the larger stink bugs especially, is to place them in a cup of soapy water to kill them. Then there is my method of just picking the stink bug up (if it’s not too creepy for you!) and throwing it out the door. If it’s cold enough outside they won’t survive to come back in.
Because the much smaller lady beetle is a “good bug” for your garden, you may want to keep them alive to have them around for their help in the spring. Sweeping them up or using a piece of stocking placed in the hose of the vacuum cleaner to collect them lets you deposit them outside in a sheltered place where they may survive the winter. Finally, the use of chemicals to kill these insects in your home should be carefully thought out since pesticides can also possibly affect pets and family members. If you feel this type of control is really necessary, consulting a professional pest control company is highly advisable.
Though these bugs may be unwanted in your home, each of these insects is just doing what is natural for them; literally coming in from the cold. Different people have different tolerances for insects but if you just want to get them out, that makes perfect sense. So good luck this winter if you have these two bugs as guests and realize that even though they can be a nuisance, both the marmorated stink bug and multicolored Asian lady beetle are two of the many fascinating insects that live in the High Country.
References:
Brown Marmorated Stink Bug. US EPA. 2022.
https://www.epa.gov/safepestcontrol/brown-marmorated-stink-bug
Brown Marmorated Stink Bug. USDA National Invasive Species Information Center.
https://www.invasivespeciesinfo.gov/terrestrial/invertebrates/brown-marmorated-stink-bug
Jim Walgenbach. Brown Marmorated Stink Bug (North Carolina). NC State Extension Publication. 2022. https://content.ces.ncsu.edu/brown-marmorated-stink-bug-1
Jim Walgenbach and Stephen Schoof. Lady Beetles. NC State Extension Publication. 2015.
https://content.ces.ncsu.edu/lady-beetles
Michael Waldvogel, Stephen Bambara, James Baker and David Orr. Multicolored Asian Lady beetles inside houses-NC State Extension Publication. 2018.
https://content.ces.ncsu.edu/multicolored-asian-lady-beetle-inside-houses
Portions of this article appeared in the Watauga Democrat (Boone, NC) on November 30, 2022.