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10/16/01 Contacts: Yard and Garden Column for the Week Beginning Oct. 19 When Good Bugs Go Bad: Ladybugs in the Home By Donald R. Lewis Ladybugs by the thousands (some claim millions) clinging to the sunny
side of the house is a common and well-known problem around the state
in the fall of the year. Then, to make matters worse, the ladybugs find
their way from outdoors to indoors and show up as unwanted guests in the
house. Where the ladybugs are particularly abundant, they will stay indoors
from now till spring. The "multicolored Asian lady beetle" (Harmonia axyridis), has become common throughout the eastern U.S. and all of Iowa. This biological control natural enemy is a beneficial inhabitant of the landscape but can be a severe household nuisance during late fall and winter. Description The Asian lady beetle is approximately 1/3 inch in length and semispherical or dome-shaped. The color is yellowish-orange to red with 19 black spots on the back that vary in darkness among individuals. The spots may be faint or missing on some beetles. Asian lady beetles, like boxelder bugs, pine seed bugs and elm leaf beetles, are accidental invaders; that is, they are "outdoor" insects that create a nuisance by wandering indoors during a limited portion of their life cycle. Ladybugs and all accidental invaders do not feed or reproduce indoors. Every ladybug found indoors crawled in through gaps and cracks in the siding or around windows and doors during September and October. Ladybugs cannot attack the house structure, furniture, or fabric. They cannot sting or carry diseases. Lady beetles do not feed on people though they infrequently pinch exposed skin. What to do The preference is to tolerate lady beetles on the outside of the house but prevent their invasion by sealing cracks, gaps and openings on the outside before the beetles wander in during late summer. Of course sealing gaps that only the insects can find is much easier said than done. Application of insecticides to the outside of the house is a displeasing possibility. Nobody starts out in life wanting to harm a ladybug, especially if you believe the old superstition that finding a ladybug brings good luck! However, the unbearable numbers that some people experience make any thoughts of tolerance and peaceful co-existence out of the question. Application of residual insecticides such as permethrin or esfenvalerate to the outside of buildings may help prevent pest entry. Spray early, spray often for best results if chemical prevention is your choice. Indoor sprays are of very limited benefit. The practical solution for homeowners in fall and winter is to sweep up and discard invader lady beetles as they appear. Lady Beetle Traps? One alternative for homeowners unable/unwilling to pursue wintertime ladybug control via vacuuming is the use of lady beetle traps as indoor collecting devices. One available trap is essentially a cardboard box with a sticky inner lining. Although sold with a pheromone, there is no indication that the beetles respond to it. If there are a lot of beetles in a building some will wander into the trap by random dumb luck and be caught. Another possibility is an indoor light trap. H&T Alternative Controls, P.O. Box 1546, Perry, Georgia 31069 (phone 912-988-9412 or 1-877-967-6777) advertises two models of black light traps for indoor lady beetle control. They retail from about $100 to $125. The traps are attached in a corner or against a wall and plugged into an electrical outlet. Ultraviolet light from the trap lures ladybugs (and probably other insects) inside. Both traps are effective only at night in the absence of competing light sources, but can be used during daytime if the room is completely dark and unlighted by windows or other light sources. H&T traps are not designed to kill lady beetles but rather to collect them for removal from the building. To remove beetles from the trap, simply brush any beetles into the lower container, open the trap and transfer the contents into a plastic bag or jar. Unfortunately, there is no data on the effectiveness of these traps against lady beetles in the upper Midwest. -30- ml: isugarden |
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