Pests with a purpose: How to combat Asian lady beetles

Signs of fall: turning foliage, fuzzy sweaters, frost on pumpkins and Asian lady beetles swarming some suburban homes.

To homeowners, they’re nuisance pests who make their way into warm, indoor climes through the smallest of cracks and crevices. To Spencer Campbell, plant clinic manager at the Morton Arboretum, they’re harmless and rather useful pests that homeowners typically can curtail with a few simple fixes that don’t involve pesticides.

Introduced more than 50 years ago, the Asian beetles help control common agricultural pests, including insects known as aphids, according to Campbell. To that end, “they provide a valuable service” by helping to maintain a healthy agricultural balance.

“They play an important role in our ecosystem,” said Campbell, pointing out that most people never notice the beetles.

“They don’t cause property damage and they don’t carry diseases,” he said, although “if they’re disturbed there are reports of a small bite which can be painful.” They also can secrete a substance that can stain surfaces.

Campbell acknowledges their “swarming activity” can be particularly annoying this time of year as the beetles seek shelter from near-freezing temperatures on flat, vertical surfaces, on sunny, south-facing sides of buildings.

They also seek shelter indoors, entering through cracks around doors and windows. To prevent that, he recommends sealing up small cracks or openings. Dimming exterior lights also can make the home less attractive, he said.

For those that make it indoors, Campbell recommends sweeping them up instead of vacuuming which causes an unpleasant odor.

Campbell and his Morton Arboretum colleagues advise homeowners to adopt an “integrated pest management” approach that incorporates biological, cultural and preventive techniques. To that end, he recommends chemical sprays only as a last resort.

“I hope we can view (Asian lady beetles) as something beyond simply a pest to remove,” Campbell said. “If we learn more about them, we can manage them more effectively.”

Homeowners with questions about how to combat Asian beetles or any other pests can visit the arboretum for help or call the plant clinic at (630) 719-2424. Email questions to plantclinic@mortonarb.org or check online resources at mortonarb.org.