You may have noticed ladybugs in your home recently, a common winter experience for people in the Triangle Area. With our mostly mild winter, ladybugs have also been active at Prairie Ridge. Not all of them are native to our area, however.
In spite of their common name, ladybugs are not bugs (insects in the order Hemiptera) and are instead beetles (order Coleoptera) in the family Coccinellidae. There are about 6000 species of ladybugs worldwide and over 500 in the US. The name Coccinellidae is based on the Greek and Latin words for scarlet and refers to the typical bright red coloration of the best-known beetles in the ladybug group. However, ladybugs come in a wide variety of colors and patterns and adult beetles can be black, orange, yellow, pink, brown, or other colors. Spot patterns can vary widely as well, with some ladybugs sporting stripes, swirls, or no patterns at all.
Ladybugs are predators as both larvae and adults and prey on aphids and other small insects. At Prairie Ridge in the summer, you can almost always find ladybugs on the Common Milkweed plants as these plants are home to hundreds of aphids. Common Milkweed contains toxins that the aphids ingest as they feed. The ladybugs that eat the aphids likewise consume the Common Milkweed toxins, processing those toxins and storing them within their bodies. The bright reds, yellows, and oranges alongside those deep blacks are an advertisement to birds and other would-be predators, one that says, "Eat me at your own peril! I'm full of toxins and will make you sick!"
So why do ladybugs come into your home in the winter? When the temperatures drop, ladybugs start to seek refuge for the season. Ladybugs in the wild aggregate in the winter, forming large groups in protected crevices. This crevice-seeking behavior may lead to ladybugs to the cracks and crevices of your warm home as well. Once one ladybug finds a way in, others may follow the chemical signals it produces and try to form groups to overwinter. Occasionally a house will attract so many ladybugs that it becomes necessary to remove them.
Non-native ladybugs have been imported into the US for over a hundred years and several exotic species have become established in our country. One imported ladybug, the Asian Multicolored Ladybeetle (Harmonia axyridis), has done particularly well here and is commonly observed in houses in winter. If you live in the Triangle Area and have seen ladybugs indoors, they are likely Asian Multicolored Ladybeetles. We have seen a lot of them at Prairie Ridge recently as well, both indoors and out. In fact, they are the most commonly observed ladybug we've seen all winter.
Some of our native ladybugs have become increasingly scarce in the last few decades and some scientists think that non-native ladybugs like the Asian Multicolored Ladybeetle might be pushing our native ladybugs out of their natural ranges. Consider helping scientists track ladybug populations by participating in the Lost Ladybug Project! When you find a ladybug, snap a photo, then visit LostLadybug.org to submit your photos. With your help, scientists are learning how ladybug ranges have changed over the past century and can direct conservation and management efforts toward threatened ladybug species.
We've seen active ladybugs at Prairie Ridge all winter, so consider bringing a camera and documenting the ladybugs you see on your next visit! You never know where you might find one lurking.
Find out more about the natural happenings at Prairie Ridge at our What Time is it in Nature Archive.