Asian lady beetles look very similar to typical ladybugs, but are distinct in appearance and behavior. Asian beetles range in color from mustard-yellow to dark reddish orange and everything in between. Spots may occur in various numbers and patterns or may be absent altogether. The key differentiator is that Asian beetles have two white, oval markings on both sides of the pronotum and may have an M-shaped marking as well.
During the crop growing season, Asian lady beetles are beneficial and feed on aphids, scale, and other pests that cause damage to plants and crops. The reason these are considered pests unlike their relative the ladybug is they reproduce quickly and are capable of having several generations per year. These fast-expanding families end up swarming homes in masses. Not only will they blanket homes and buildings by the hundreds and thousands, but they are masters at structural penetration.
Asian multicolored lady beetles were introduced into the United States in the 70’s to control crop pests.
They will hang out in fields and places where food is plentiful until the temperature takes a significant drop in the fall. Once the cold snap triggers the overwintering mechanism in these beetles, they will typically wait about five days and then actively seek a place to overwinter. Once they get settled into a home, changes in heat levels in their nesting spots from central heating and air systems may wake them up and cause new waves to enter the home. In the spring, they will be seen in droves as they come out of overwintering stages to feed and start the reproductive process over again.
Asian beetles are not like other bugs that are of little concern if only a few are seen here or there. Even a few of these beetles may trigger aggregation behavior that will draw the hoards toward the structure. Since Asian lady beetles are negatively geotropic, they find their way up under siding and other seams of the home easier than many other insects. They will invade wall voids in their overwintering efforts and will often times show up in upper levels of homes and pop out in master bath areas and 3-season porches. They are not afraid to work their way into basements and any other part of the home they see fit. If having thousands of these swarming the home and moving in and out of voids and parts of the home were not enough, their presence may attract dermestid beetles as well.
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