Column: Time for annual invasion of the ladybug beetles

     As the day length diminishes, temperatures begin to drop, leaves begin to change color, and fields are harvested, little orange ladybugs will magically begin appearing in and on our homes and outbuildings. Are you prepared for the ladybug invasion?

     Around 100 ladybug beetle species have been identified within the state of Iowa. Many of our native species are found in small numbers – overwintering under the bark of trees, under leaves, mulch, or plant thatch, or in woodpiles or rock retaining walls. They do not routinely show up at our homes.

     The one species we are most familiar with in recent years is the multicolored Asian lady beetle. Intentionally introduced into the United States as early as 1916 to help control insect pests the multicolored Asian lady beetle can be found in crop fields, gardens, and vegetated areas where they feed upon aphids and other plant pests. They are known for the way they undauntedly congregate around homes and buildings during the warm autumn days on their search for the perfect place to spend the winter.

     The Asian lady beetle varies in color from a familiar and most common yellowish-orange to an almost red color. They can have 0-19 black spots on their backs, and are easily identified by a black “M or W” (depending on how you look at it) shaped mark behind their head.

     Asian lady beetles are considered “accidental invaders,” outdoor insects who create a nuisance by wandering indoors during a limited portion of their life cycle. They do not feed or reproduce indoors, and will not attack your furniture, fabric, or home. On the other hand, if ladybug beetles are squashed they will leave a foul-smelling yellow orange liquid that can stain fabrics. This yellow liquid is what protects lady beetles from being eaten by predators. The bright color of the lady beetles helps to warn predators of their nasty taste. Although they cannot sting and do not carry disease, they can occasionally pinch exposed skin, if threatened.

     As Asian lady beetles seek a place to overwinter they are attracted to homes, sunny sides of buildings, windows, and outdoor fixtures where they sometimes find their way inside. In the outdoors they would normally gather together in groups under bark or leaf litter and spend the winter dormant.

     To prevent unwanted guests in your home it is advisable to seal all cracks, gaps, and openings that lead to the inside. If some do make it through your defense, a practical solution for removal is to sweep them up and discard them back outdoors well away from your home. Some people find a simple hand vacuum designated for ladybugs a great option – but remember it may smell like a ladybug when you are done.

     Although lady beetles may be a temporary pest in the autumn, they work hard for gardeners and farmers throughout the spring and summer. An adult lady beetle’s diet consists of up to 50-60 aphids per day.

     For more information on multicolored Asian lady beetles in Iowa visit https://hortnews.extension.iastate.edu/2015/10-23/ladybug.htm