I used to think those tiny cute little ladybugs were quite harmless. I used to let them land on my shoulders while hiking in the woods and carry them along as friendly hitchhikers. I read with glee about these insects being used by farmers as "natural" ways to control pests. However, my eyes were opened quite recently after hearing about several studies presented at the American Academy of Asthma, Allergy & Immunology's 2006 Annual Meeting with regard to an invading species. There is a very real ladybug threat in a matter of speaking. The little monsters causing havoc are Asian Ladybird (Ladybug) beetles (Harmonia axyridis) and they can be quite nasty. In America the name "ladybird" has been popularly Americanized to "ladybug", although these insects are actually beetles (Coleoptera), and not bugs (Hemiptera). Furthermore the Asian beetles should not be confused with the European Coccinella septempunctata which is the friendlier seven-spotted ladybug.
These ladybugs from Asia are multi-colored and a bit larger (5 to 8 mm in length) than most native American species. In Japan they are used intentionally to control arthropod pests and quite by accident they found they way to American throughout the 20th century. By the mid-1990's they could be found from the Canadian boarder to Florida and from coast to coast.
Most Asian beetles tend to be yellow to red in color and have a varying pattern and size of spots from no spots to around nineteen. Unlike our native ladybug these Asian beetles can inflict a rather painful bite. Additionally, H. axyridis will exude a foul-smelling, viscous yellow defensive chemical (when disturbed) that may be an allergen to may people. And this is where the problem lies.
When the weather gets cooler ladybugs come into homes and are usually found in attics, within walls and around windowsills. Homes that are infested with this beetle often reveal tiny yellow dots (the defensive compound they release) on the walls as a tale-tell sign of a problem. There can be hundreds or even thousands in your house when there is a significant infestation. This species of ladybug are of special consternation to people who suffer with entomophobia (whose with a fear of insects) as you can imagine.
H. axyridis adults deposit their eggs in or near prey infestations. They prey upon many species of injurious soft-bodied insects such as aphids, scales, and psyllids and that is why many farmers and gardeners don't mind them so much. Eggs take about 4 days to hatch while the larva stage lasts about 2 weeks. Adults amazingly can live up to 2 to 3 years in optimal conditions. The larvae are larger than most native ladybird larvae and are especially fond of crapemyrtle aphids, found only on crape myrtle. Many of our native beneficials (those bugs that eat pests) also feed on crapemyrtle aphids. It is suspected that H. axyridis may be responsible for reduction in the numbers of native beneficial beetles including other ladybug species through cannibalism and by competing for prey. They tend to take over and kill off more tame species, much like the what the killer bees of Africa (Apis mellifera scutellata) do to other subspecies of honey bees. Another example of this unhealthy competition is the Snakehead fish (another Asian import) which some experts worry will have an untoward effect on native fish in our lakes. The Snakehead has a veracious appetite, is resilient and can live out of water for hours. This fish is a menace because it has few natural predators and can deplete lakes of indigenous fish. The same rule may hold true for H. axyridis.
Besides sustaining a painful bite H. axyridis is more worrisome to those prone to allergic reactions. Allergic reactions to these ladybugs are rather common and can result in sneezing, rhinorrhea, itchy eyes as mild reactions to those of cough and shortness of breath with wheezing as more serious reactions. Rashes have also been reported. To an asthmatic with sensitivity to this beetle's antigen this can spell some real trouble. Researchers have found that up to 21% of people tested (especially in rural areas of the country) exhibit sensitivity. That is similar to cat (24%) and cockroach (27%) sensitivity. Mild reactions are not great problem, but should a hypersensitive asthmatic get exposed the reactions may have more serious consequences.
JP Saleeby, MD is assistant medical director of the ER at LRMC, Hinesville, GA. He is also adjunct professor at GSU, Statesboro, GA. He has recently published a book on herbs entitled: Wonder Herbs: A Guide to Three Adaptogens and can be reached for comment at jpsaleeby@aol.com
Reference:
Clinical Rounds, Family Practice News, April 15, 2006
http://creatures.ifas.ufl.edu/
http://www.nysaes.cornell.edu/
http://allergies.about.com/
http://www.insecta-inspecta.com/bees/killer/
http://fishing.about.com/
