Spring brings with it many insects emerging from their winter hibernation. The multi-colored asian lady bug, or ladybird beetle, the boxelder bug, and the cluster fly are all common invaders in the early spring. The life cycle of each of these pests depends upon overwintering in a sheltered location during the winter. That sheltered location usually ends up being the walls of a residential home.
The life cycle and appearance of these insects is very different from one another. Lady bugs are beetles that undergo complete metamorphosis and are usually beneficial insects, until they invade our homes. Boxelder bugs are true bugs with gradual metamorphosis. Boxelder bugs suck the sap from boxelder trees and related species (maple family among others) during the spring and summer months. Their bright red nymphs can often be seen at the base of trees during the late spring and early summer months. Cluster flies are a particularly annoying pest. Cluster flies are very similar in appearance to house flies, but their life cycle is very different. Cluster flies are parasites of earthworms until they have reached adulthood. Cluster flies tend to cause the greatest distress in homeowners when they appear indoors in large numbers. These disparate insects have one thing in common, each of them will invade the walls of a home in order to overwinter.
These pests will overwinter in a southern exposure (sunny side) inside the walls of a home. They will emerge when the temperatures hover in the 60’s or higher for several days in a row. In a perfect world, these insects would always find their way back outside, but, unfortunately, individuals end up getting lost and find their way to the interior of the home. Window and door frames, baseboard cracks, and vents are common places for these insects to emerge inside.
Control efforts are usually confined to crack and crevice treatments around their emergence points. Dusts, sprays, or aerosols can be used to prevent more insects from entering from those locations. Individuals on the interior are best controlled with a vacuum.
On the exterior, these insects will often congregate in large numbers at the foundation, and around doors and windows. A residual spray applied to these locations will usually take care of the problem, however, more than one treatment may be necessary when large numbers are present.