Asian ladybugs

Asian ladybugs are becoming more numerous with the onset of winter. Ladybugs, or lady beetles, are small insects usually thought of as useful in controlling aphids, and are of the coccinellidae family of beetle. Often associated with children’s stories, ladybugs are regarded as cute, small insects about one-quarter inch in length with colorful round bodies of bright orange or red with black spots.

Credit: wikimedia.org - John Alan Elson

In the fall, Asian lady beetles (harmonia axyridis) are the ones usually finding their way into homes to hibernate over winter. The Asian ladybug was introduced by the U.S. Department of Agriculture in the 1980s to help control aphids and has spread across North America in the last 20 years. It is now the most common variety we see. The Asian variety is often orange with spots of varying numbers, from no spots up to 22 spots.

Asian ladybugs are good at eating aphids and have helped control invasive soybean aphids, also introduced from Asia. All ladybugs have a chemical with a disagreeable smell that is part of their defense against predators and which can cause staining. Asian lady beetles produce more of this chemical than native lady beetles and can impart an off-taste to fruits such as grapes when feeding on aphids.

It is almost becoming a rarity to see the varieties native to our area. The 12-spotted or pink- spotted lady beetle (Coleomegilla maculata) and the nine-spotted lady beetle (Coccinella novemnotata) are native ladybugs. The nine-spotted variety is occasionally seen in Frederick County and has a spot behind the head that is split, with half on one side of the shell and half on the other, and four full spots on each side, for a total of nine spots. The native ladybugs are less prone to massing for hibernation, and consequently are not seen in homes. Aside from the energy efficiency aspects of sealing air infiltration into our homes, tightening up the building envelope is also a good way to reduce the numbers of ladybugs we see with the change in seasons.

Article by Tom Anderson, FCFCDB member

Nature Notes for 12/6/2015