Ladybugs - Multicolored Asian Ladybird Beetles
Helping Nebraskans enhance their lives through research-based education.
Multicolored Asian Ladybird Beetles - Ladybugs
by Barb Ogg, PhD, Extension Educator
Some years, the extension office has handled hundreds of calls about ladybugs invading homes. We take most of these calls in fall, but a surprising number came in the spring when beetles, still inside wall voids, became active as temperatures warmed up.
Those who had ladybug invasions last year, should expect a repeat, unless you have taken measures to seal cracks and crevices around siding, windows and doors. Ladybugs squeeze through these cracks and crevices in order to find an insulated place to hibernate during the winter.
Most of us know that ladybugs are good insects. They have a long-standing reputation of ridding garden and crops from insect pests, especially aphids. In medieval Europe, people believed the ladybug was divinely sent from heaven to protect crops. They called it the "Bug of Our Lady," a reference to the Virgin Mary. Over time, the name was shortened to 'ladybug.'
What is the nursery rhyme about?
Ladybug, ladybug, fly away home, Your house is on fire, your children do roam. Except little Nan, who sits in a pan, Weaving gold laces as fast as she can.
This verse started in ancient England as a warning to the ladybugs crawling on old hop vines. After harvest, the farmers set fire to the vines to clear the fields. The adult ladybugs could fly away, but the larvae could only crawl. The unfortunate pupa (Nan in the rhyme) was fastened to the burning plants.
We've grown up thinking about ladybugs as being good, so it is a radical shift to think about them as being a pest. What's happened here? Is this a case of a good insect gone bad?
Multicolored Asian Ladybird Beetles The offending ladybug is one species, called the Multicolored Asian Ladybird Beetle (MALB). This lady bug species is larger than many of our native species. "Multicolored" refers to the tremendous color variations in this species, ranging from black with two red spots, to red with 19 black spots, with every combination in between. The most common color seems to be deep orange. The thorax of these beetles usually has black markings on a white background in the shape of an irregular "M".
The MALB, recognized as a voracious feeder, was introduced several times in the U.S. as a biological control agent for the control of aphids and other pest insects.
The biggest problem is where the MALB chooses to overwinter. In its native habitat in Asia, large numbers of MALB aggregate and overwinter in cracks and crevices within cliff faces. Since cliffs are not readily available in Nebraska, the next best things are tall houses!
Researchers studying the MALB now recognize they are attracted to tall houses that are often all by themselves in the landscape, often near a grove of trees. This description sounds a lot like farmsteads and acreages in our rural areas. Given the MALB is a voracious feeder of soybean aphid (also native to Asia), rural homes are very susceptible, although folks who live in town are not immune from MALB invasions.
The number of MALB that invade varies from a few individuals to thousands. This can be a major nuisance to the family whose home becomes the residence of choice for MALB.
This ladybug species has a number of other undesirable qualities.
***MALB secretes a foul-tasting chemical from their legs, which makes them unpalatable to their enemies. This secretion can stain fabric and wallpaper.
***Large infestations of MALB have a definite odor.
***MALB has been reported to be an asthma trigger in a few sensitive individuals.
***MALB will bite. It isn't particularly painful, but it is annoying.
***They feed on grapes and other fruits. When crushed, their bodies will taint wine and affect its taste – a potential problem for vineyards.
Because these ladybird beetles congregate in enormous masses, the sheer numbers of these beetles can be very frustrating for homeowners. Some of the following tips may be helpful:
Try to minimize entry points:
- Locate entry points and seal cracks and crevices with caulk to prevent entry.
- Make sure window screens and doors are tight-fitting. Use weather stripping.
- Concentrate initial efforts on the south and west sides of structures.
Once beetles are inside, the following suggestions may be helpful:
***Do not swat or smash lady beetles. They have body fluids that can stain draperies and wall coverings.
***Using insecticides inside the home will not prevent other beetles from coming inside and has limited effectiveness unless sprayed directly on beetles.
***Vacuuming lady beetles is as effective as insecticides and is recommended strategy.
Helpful tip when using a vacuum cleaner: If large numbers of MALB get sucked into the interior part of the vacuum cleaner, their secretions will cause the vacuum cleaner to smell like MALB every time it is used. To prevent this, one can insert a knee-high nylon stocking into the hose wand to capture the beetles before they are sucked into the vacuum cleaner body. Insert the knee-high stocking into a connection joint in the wand so it forms a bag inside the hose and a portion of the stocking folds over the outside of the wand to secure it in place when the wand is put back together. After sucking up the beetles, remove the stocking and dispose of the beetles.
Ohio State University Extension has done some research on spraying the exterior of homes to prevent these beetles from coming inside. Timing of treatment is extremely important. Too early and the chemical will lose its effectiveness. Too late and the ladybugs will already be inside. It would be impractical and nearly impossible to control them once they're inside walls.
Ohio State University Extension suggests that repellent insecticides can be applied to exterior siding, including around eaves, attic vents, roof overhangs, and doors and windows. Pre-test a small area to ensure that the chemical treatment does not stain or discolor siding. Wettable powder and microencapsulated formulations seem to be most effective against ladybird beetles. These formulations are not readily available to the homeowner, so it may be necessary to enlist the services of a licensed pest management professional. Residual pyrethroids include a variety of active ingredients, such as bifenthrin, cyfluthrin, cypermethrin, deltamethrin, lambda-cyhalothrin, or tralomethrin.
For more information about using insecticides, check out the following websites:
Ohio State University Cooperative Extension: http://ohioline.osu.edu/hse-fact/1030.html
West Virginia University Extension: http://www.wvu.edu/~agexten/ipm/insects/ladybeetle.htm
Timing is important. If the treatment is done too early, the insecticide will lose its effectiveness and repellency. If insecticides are applied after the first cold snap of fall, the lady beetles congregating indoors will be unaffected and it may be a wasted treatment.
Because of the expense and difficulties of an exterior whole house treatment and the problems with timing, this type of treatment may not be practical way of dealing with multi-colored Asian lady beetles.
Again, vacuuming lady beetles is as effective as insecticides and is recommended strategy.
The information on this Web site is valid for residents of southeastern Nebraska. It may or may not apply in your area. If you live outside southeastern Nebraska, visit your local Extension office
Nebraska Extension in Lancaster County
Web site: lancaster.unl.edu
444 Cherrycreek Road, Suite A, Lincoln, NE 68528