The Homeowners Column

The Homeowners Column

Ladybugs Can Be a Real Nuisance

Photo of Sandra Mason

Sandra Mason
Extension Educator, Horticulture
slmason@illinois.edu

Ladybugs seem to be the latest topic of conversation; conversation which tends to include many expletives. In the garden, ladybugs eat lots of bad bugs including aphids and scale. When ladybugs enter our homes they quickly lose their title as good bugs. Even though there are several species of lady beetles in Illinois, one is giving the rest a bad name. Asian multicolored lady beetles are migrating now and eyeing your house as a winter retreat.

Besides being a nuisance indoors, ladybeetles can and do bite. Although they have no venom, the bite hurts and can leave a red mark. In my experience the Asian multicolor seems to bite more than the other species of ladybeetles in Illinois. Maybe they are just hungrier.

The Asian lady beetles are one fourth inch long and are the VW bug dome shape. They usually have orange wingcovers with 19 black spots. No need to count the spots. Their multicolored name comes from the variety of color possibilities ranging from tan to red and the spots may be very small to absent, to large and obvious.

Both the young larva and the adults feed on a wide range of insects. Asian multicolored ladybeetles are very good at controlling aphids on trees and shrubs. They were first imported into Georgia to control the pecan aphid.

In their native areas in Japan, the Asian multicolor ladybugs spend the winter in cracks and crevices of cliffs. Cliffs are tough to find in central Illinois so what is the next best upright thing around? Our homes of course. In the fall they start their migration flights. They are particularly attracted to light colored structures with sunny exposures. There they congregate in large herds on the sides of buildings. They wander around and enter buildings through cracks between siding, around windows, around roof flashing and overhangs. Or they may fly through doors as people go in and out.

If there is no heating in the building, the beetles just snuggle together and wait for spring. In heated buildings especially on bright sunny days they may start flying around trying to escape. These eventually die on the windowsill.

The good news is ladybugs don't reproduce or feed while they are indoors. Controlling these insects indoors consists of vacuuming or your best scoop and toss outside method. Soon they will all have gone outside one way or the other.

Insecticide sprays are likely to have little to no effect on hard-shelled insects that are not feeding unless you get lucky and happen to drown a few. Preventing ladybeetles from entering is the best control measure. Caulking cracks and crevices around windows, along the foundation and around doors will help reduce the numbers that can make their way indoors in the fall.

There are traps available that show good results under specific conditions. H&T Alternative Controls sells two different light traps. These are not designed to kill the ladybugs, but trap them so they can be removed. The traps are designed for use only on the inside of buildings and not designed for use outdoors. They are effective only at night as beetles are attracted to the light and best used in rooms without other lights. They work best when temperatures are above 75 degrees. I guess for entertainment you turn up the heat, turn off all the lights and watch the ladybugs fall into the trap. H&T 120 is $98.50 and 360 unit is $125 plus about $8 shipping. H&T Alternative Controls, PO Box 1546 Perry, Georgia, 31069 or phone 912-988-9412. No product endorsement is intended.

Remember ladybugs are actually good bugs outside. Repeat this over and over to yourself as you are scooping them up from your windowsills.

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