September 28, 2009

Growing Green
with Extension Educator Robin Trott

Asian Lady Beetles

It’s that time of year again. The time when Asian Lady Beetles swarm up the sunny sides of tall or prominent buildings looking for winter shelter, preferably full of food, otherwise known as YOUR HOUSE!! YUCK! These ladybugs are natives of eastern Asia, and were originally introduced in California in 1964 by the US Department of Agriculture as a biological control for Pecan Aphids. Additional releases from 1978-1982 established them in the southern and eastern United States. Although they were never released in Minnesota, they have migrated here from other areas and have now established themselves in our fields and our homes.

They seem to be attracted to buildings with contrasting light and dark areas, and are found in larger numbers on buildings adjacent to wooded areas. They begin to emerge on the second day of temperatures above 65 degrees following freezing or near freezing temperatures. Usually, these conditions occur between late September and late October.

To prevent lady beetles from gaining access to your home, check the exterior for spaces and cracks that will allow these bugs easy entry. Remember that lady beetles can fit through openings as small as 1/8 inch. Seal cracks around windows, doors and fascia boards with caulk. Don’t forget to check areas where cable wires, phone lines, dryer vents and other utility wires and pipes enter your home. Use expandable spray foam, steel wool or copper mesh to keep these areas beetle free. Make sure your window and door screens are intact, and install door sweeps or thresholds on all exterior entry doors and rubber seals at the bottom of your garage doors.

Exterior insecticidal barriers can be applied before these insects enter your home. (Usually in late September or early October.) Choose an insecticide that contains one of the following: bifenthrin, cyfluthrin, cypermethrin, detla methrin or permethrin. Make sure to read the label carefully and precisely follow the application instructions. (More is not always better!!)

If the lady beetle has already gained access to your home, indoor insecticides aren’t effective in preventing addition bugs from entering. (Although I have found that Raid works on large nests of indoor bugs if you can find them.) The best solution is to remove unwanted bugs with your vacuum. It might be necessary to change the bag frequently, because the vacuum doesn’t necessarily kill the beetles, and they exude a smelly liquid that will make subsequent vacuuming unpleasant.

Another suggestion is to rubber band a nylon stocking around the end of the vacuum intake hose prior to attaching the floor extension. This works as a net to catch unwanted lady bugs and keep them from entering your vacuum bag. When finished vacuuming, simply remove the stocking, use the rubber band to close the end, and toss out the lady bugs in the garbage.

Good luck in your bug battles, and, as always, happy gardening! Next time- Box Elder bugs.

House, n. A hollow edifice erected for the habitation of man, rat, mouse, beetle, cockroach, fly, mosquito, flea, bacillus, and microbe.

The Devil's Dictionary (1911) ~Ambrose Bierce