We see them in the news from time to time: some kind of pest that few have ever seen, and they are causing problems. You’ve may have recently heard of Japanese climbing fern, zebra mussels, and raspberry crazy ants. If they are problematic, we call these non-native pests “invasive.” According to the Federal Registry, Executive Order 13112 defines invasive species as “a species that is non-native (or alien) to the ecosystem under consideration and whose introduction causes or is likely to cause economic or environmental harm or harm to human health.”
So, what about the irregular looking “lady bugs” that our office got calls on earlier this week? These are Asian lady beetles, and they are making their annual move into protected areas to spend the winter. And your home is a place they love to spend the winter. Lady beetles are insects that are absolutely beneficial. They are not invading your home to cause problems, only to stay warm. The lady beetle does not chew or bore holes in walls, nor do they eat carpet or any food in the pantry.
Lady beetles have been considered one of our most beloved insects. They are in stories, a good luck charm for some, and I’ve even seen kids dress up as one for Halloween. Most people grew up calling the lady “bugs.” If you grew up and don’t remember seeing as many, you are absolutely correct. There is a native lady beetle that is harder to locate and a multitude of non-native ladybug insects that are native to Asia but in the past few decades have spread to many areas of the United States.
This beneficial (yet sometimes controversial) Asian relative was released in the United States as early as 1916. More were released in the late 1970’s and again in the early 1980’s. It has taken years for the populations to spread, but now large populations are found in many areas of the south.
The lady beetle is attracted to lighter colors such as whites, grays, and yellows. They enter homes through cracks and crevices. During warm winter days and early spring, the lady beetle may become more active searching for an exit. Like other non-native species, these Asian lady beetles grow, reproduce, and spread rapidly. Species that become invasive succeed due to favorable environmental conditions and lack of natural predators, competitors and diseases that normally regulate their populations.
Indeed, there is a wide variety of plants, insects, and animals from exotic places. As non-native, invasive species spread and take over ecosystems. They decrease biodiversity by threatening the survival of native plants and animals. However, many exotic species do not cause harm to our economy, our environment, or our health. In fact, the vast majority of species do not survive and only about 15% of those that do go on to become or harmful. Fire ants, native to South America, come to mind as another insect that has spread throughout the south.
What about insects such as the Asian Lady Beetle? While not exactly one of our own native insects, this critter does a tremendous job of controlling other, detrimental insects in your landscape. The lady beetle is an effective and natural control for harmful plant pests such as aphids, scale, and other soft-bodied arthropods. One adult lady beetle may eat over 5,000 aphids during its lifetime.
Adult lady beetles can have a variety of colors and spots. The larvae are soft-bodied, gray and orange, and covered with rows of black spots. While they cause no harm, their overwintering habits inside people’s homes cause them to be a nuisance.
No real control of these beneficial insects is warranted as it is for termites or destructive insects. Homeowners can prevent them from entering the home by caulking exterior cracks and crevices. And the only “control measures” for them would be sweeping and vacuuming them up to release them back outside.