Environment DEC
From the December 2005 issue
The Beetles Make Another Come Back - by Peter Jentsch
Rhythms, like the changing of the seasons, or recurring styles of clothing and music, become more familiar as we grow older. I heard my teenage son singing a classic tune from the Beatles' Abbey Road album. It was a reminder of my own teenage enjoyment of the "fab four" and how I, through my son, have suprisingly contributed to the rhythm of the next generation of Beatles enthusiasts. It was a reminder of the periodicity of human history, and the somewhat predictable cycles of nature.
The Beetles Invasion
Asian Ladybird Beetle - photo
by Scott Bauer
Each fall, the beetles invade our homes once again, making something of a predictable come back. They are not from Great Britain, though they were originally foreigners from a distant continent. The Asian multicolored ladybird beetle, Harmonia axyridis, hails from Asia-Japan to be more precise. These colorful invaders continue their cycle of seeking refuge in our homes before the severity of winter sets in.
In their native land, the adult beetle, or ladybug as we most often call "her," finds crevices in rock walls or cliffs for suitable overwintering harborage. In the Eastern U.S., instead of cliffs, they use the openings of soffits, window and door seams, and cracks in siding and foundations, to gain access to protected places where they lie fairly dormant for the winter.
They are first seen congregating on the sunny sides of buildings. Many move under leaf litter, logs, or other protected areas after the first frost. Those that stay often access south or southwestern facing rooms. On warm winter and spring days, they emerge from wall voids and become active and numerous. They often emerge in large numbers and begin crawling on windows, walls and light fixtures. When disturbed, they can secrete a foul-smelling orange-colored fluid that can spot and stain walls and carpeting.
"They may be here in record numbers, but multicolored Asian lady beetles don't sting, carry human disease or eat wood, clothing, food or houseplants." stated Janet J. Knodel, entomologist with the NYS Integrated Pest Management Program (IPM) at the NYS Agricultural Experiment Station. "They have been reported to bite, but it is rare and harmless." On the lighter side, they have been known to incite insectophobes (people afraid of insects) to swoon and faint like the hundreds of teenage girls in 1964 at the very sight of the Beatles on stage.
A Beneficial "Invasive Species"
Many insects in the United States are non-native. They have been introduced accidentally and often transported on agricultural or other commercial products. Most introduced insects are pests, damaging crops and forests, or of public health concern. Millions of dollars are spent each year managing these insects. The Asian multicolored ladybird beetle is an exception. It was purposely introduced into the United States as a biological control agent to help reduce populations of aphids, psyllids, and scale.
Although the USDA in California officially introduced the beetle in 1916, 1964 and 1965, some researchers think current beetle populations originated from accidental introduction of the species during freighter activity in New Orleans in the early 1990s. Since then, this exotic lady beetle has propagated and moved rapidly from the South to the Northeast and eastern Canada, and is now widely distributed across much of the United States east of the Mississippi River.
The millions of forested acres throughout the Hudson Valley provide a vast habitat for the Asian multicolored ladybird beetle. The beetle also inhabits ornamental and agricultural crops including roses and apple, helping reduce pest populations and the damage they cause. Each larva can consume 600 to 1,200 aphids during its development, and an adult beetle is capable of eating 90 to 270 aphids per day.
Beetles Biology
Adult Asian lady beetles are oval, convex, about 1/4-inch long, and pale yellow-orange to dark orange-red. They often have several black spots on the wing covers, although in some cases, the spots may be indistinct or entirely absent. In Asia, this beetle occurs in at least 100 different color forms including black with orange spots. Most beetles have a small, dark "M"-shaped marking on the whitish area directly behind the head.
Their eggs are yellow, oval-shaped, and typically laid in clusters on the undersurfaces of leaves. The developing larvae are often red and black, and shaped like tiny alligators. Larvae complete their development on plants where their food is abundant. The immobile pupal (cocoon) stage remains attached to vegetation by its molted skin, but occasionally may be found clinging to the exterior walls and foundations of buildings. The average time from egg to adult is about one month, and there are multiple generations per year.
As spring approaches, beetles overwintering in and around structures will disperse outdoors to play their important role as beneficial insects. Lady beetles unable to find their way outside will eventually succumb to a lack of food. Lady beetles rarely injure humans, nor can they breed or reproduce indoors as other pests can. Nonetheless, some people will not tolerate insects of any kind in their homes. Hospitals, food processors, and similar hygienic establishments have zero tolerance for contaminants of any kind. Given the varying levels of tolerance, management options should be considered.
Reducing Infestation
An important method of reducing ladybird infestations is through preventative pest proofing. Begin with the obvious entry areas in your home. Adjust or install tight-fitting door sweeps or thresholds at the bottom of all exterior entry doors. Gaps under sliding glass doors may be sealed with foam weather-stripping. Seal utility openings where pipes and wires enter the foundation and siding, e.g., around outdoor faucets, receptacles, gas meters, clothes dryer vents, and telephone/cable TV wires. Holes can be plugged with caulk, cement, urethane foam, steel wool, or copper mesh. Caulk cracks around windows, doors, siding, and fascia boards. Repair damaged window screens and install screening behind attic vents.
The most efficient way to remove ladybugs, once they are indoors, is with a vacuum cleaner. If you wish to release beetles outside, place a handkerchief or fine mesh stocking between the vacuum hose and the collection bag to act as a trap. A broom can also be used to remove beetles indoors, but is more likely to cause staining to walls or other surfaces. Since the Asian multicolored ladybird beetle will be cycling with us for some time, we might as well turn up the music, break out the vacuum and start the emigration process.
Editor's Note: Peter Jentsch is a research entomologist at Cornell University's Hudson Valley Laboratory. For more information on beneficial and harmful invasive species, see "Related Links" below.
