March 13, 2008
Asian ladybeetles (Harmonia axyridis) are an exotic species from China, but they are also mighty beneficials. Each day, a single adult can eat up to 270 aphids or other small insects that could damage your garden plants, and each larva will devour 600 to 1200 aphids during its 12- to 14-day feeding period. Some of that bug-nabbing will happen in your garden, but most of the action takes place in the treetops.
Light-colored buildings near wooded areas attract the attention of thousands of Asian ladybeetles in fall, and the only way to keep them out is to seal all open crevices and keep south-facing doors and windows tightly closed when they are swarming.
In spring, most of the ladybeetles in your house will leave unnoticed the same way they came in; others will leave freely if you remove screens or storm windows and open warm windows an inch or two at the top.
Should you collect and release beetles that won't leave on their own? According to Dr. Ted Cottrell, research entomologist at the USDA's Southeast Fruit and Nut Tree Research Lab in Byron, Georgia, in terms of control of other insect pests, the number of beneficial beetles you might capture and release outdoors is insignificant compared to the outdoor population as a whole. “From a convenience standpoint, get rid of them using your most effective and easiest method — dead or alive,” advises Cottrell.
The method of choice for most folks is to vacuum them up. To keep from having to change your vac bag or canister, place a thin sock or knee-high stocking between your vacuum's hose and head before quickly doing the deed. (See an illustration of that trick here). Special long-handled “bug vacuums” are great for reaching high corners; folks who think the only good spider is outdoor spider love them.
If you're faced with overwhelming numbers of beetles indoors, collect them at night with a light trap like the one developed by the Integrated Pest Management team at Ohio State University. The trap makes use of milk jugs and other materials you can buy at any hardware or discount store, and is designed to be hung from attic rafters.
After months indoors, Asian ladybeetles are dehydrated and hungry, so you also have the option of coddling the poor wanderers until the weather warms. Asian ladybeetles usually drop straight down when disturbed, so it's easy to collect them in a wide-mouth quart jar furnished with some apple peelings and a damp paper towel, and covered with a thin cloth. Within minutes the beetles will be quenching their thirst and filling their bellies. They will be more than content in their “spa” until the weather warms up and you can release them outdoors.
Photo by Barbara Pleasant