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LADY BEETLE SWARM RAISES HAVOC WITH GOLF SWING
I read a news alert a few weeks ago from Bill Hutchison, University of Minnesota professor of entomology, predicting that "if we have some warm days (> 60 degrees) in October, to be prepared for some significant flights of multicolored Asian lady beetles (MALB)."
Last Saturday afternoon, my wife and I drove to Alexandria and the constant taps on the windshield signaled that the flight had begun.
Back home on Sunday, we decided to play a round of golf, since the golf course appeared empty. Apparently everyone was indoors watching the Twins being defeated by the Yankees.
If the MALB flight began on Saturday, it was in full swarm mode on Sunday. The beetles seemed to delight in interfering with our golf swings. At one point, as we walked back to our golf cart after sinking our putts for birdies (yeah, right), the white foam seats on the golf cart appeared almost yellow from the hundreds of lady beetles that had taken up residence during the few minutes we were putting.
Without question, the MALB are a nuisance. I also discovered this fall that these pesky insects bite flesh. Compared with termites or houseflies, however, they have some redeeming values.
Native to eastern Asia, MALB were first detected in the U.S. in 1988 in Louisiana. It has been debated whether MALB arrived in the U.S. through intentional releases for biological control or through accidental seaport introductions. Since its initial detection, MALB have spread rapidly to cover much of the continental U.S. and parts of Canada. MALB were first detected in Minnesota in 1994.
The coloration of MALB adults ranges from orange to red with zero to 19 black spots to black with red spots.
In its native range, MALB are a known predator of aphids and other soft bodied insects. The potential of MALB as a biological control agent in the U.S. is becoming apparent. Unfortunately, MALB, like many other exotic insects, may also have adverse impacts on humans and the environment.
MALB adults typically live for one to three months, but may live up to three years. In autumn, MALB adults migrate from fields and forests to buildings and other prominent objects on the horizon. In Ohio, researchers have shown that migratory flights generally begin on the first day with temperatures exceeding 68 degrees after the first cold spell with temperatures dropping to near freezing. (That was Saturday and Sunday!) Upon arriving at a building or other structure, MALB seek out cracks or holes, in which they will spend the winter in clusters of few to many individuals.
The arrival of warm temperatures in spring stimulates dispersal from over-wintering sites and mating of MALB. Adults then seek out colonies of aphids. The eggs of MALB are generally laid in clusters of 20-30 on the underside of leaves near aphid colonies. An individual MALB female may lay up to 1,600 to 3,800 eggs. At temperatures near 84 degrees, development from egg to adult requires about 18 days. The developmental rate will increase with increasing temperature. In the U.S., two generations of MALB are generally observed per year.
MALB are voracious predators of numerous aphid species and also feed on mites, psyllids, scales, and beetle, moth and butterfly larvae. When other prey is scarce, MALB feed on pollen and nectar. Through its larval stages, MALB may consume up to 370 aphids. MALB adults will also consume up to 65 aphids per day.
MALB have proven to be an effective biological control agent. Minnesota soybean growers only wish that the millions of MALB flying around now had made their appearance last summer when aphids caused heavy damage to the soybean crop.
Most homeowners have discovered that MALB, when disturbed or crushed, emit an orange liquid that can stain carpet, furniture or drapes. Some people develop an allergic rhinoconjunctivitis to MALB. Many people are caught off guard by the fact that MALB bite humans, especially in the fall.
The best way to keep MALB out of homes is to seal cracks or holes through which MALB enter the house. Second, various black light traps are available for trapping beetles after they enter a home. Third, synthetic pyrethroid insecticides can be used on home exteriors to prevent MALB from entering the home. Deltamethrin and bifenthrin are both very effective against multicolored Asian lady beetles. Due to concerns about human exposure to pesticides, it is recommended that pesticides be used only if other management tactics are unable to suppress MALB to tolerable levels.
Once you find lady beetles inside your home, the only real control is to vacuum them and discard the bags. Spraying lady beetles indoors with insecticides has limited value and does not prevent lady beetle from entering homes.
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