Photo credit: combatbugs.com
These unassuming looking lady beetles are anything but ladylike; they are known to present themselves amongst pollen, fruit and harvested grapes and may taint a wine vintage with a repulsive blend of peanut butter, decaying spinach, blue cheese and sawdust flavor. Yuk!
These lady bugs were introduced as a biological pest control agent to control the aphid (sap-sucking plant lice) populations, which are often found to plague greenhouses. In some cultures they are also considered to be a sign of good luck. Although introducing the Harlequin can offer benefits, it certainly has a darker side, too. Along with aphids, these insects greedily prey on soft-bodied arthropod pests, other lady beetle species (including the beneficial kinds) and even each other! Conservationists fear that the Asian Lady Beetle will out-compete native beetle species.
The Asian Lady Beetle (“Harmonia axyridis”) is also known as the Harlequin Beetle due to its many colour variations. These typically range from orange to red hues, with black spots. As its name indicates, the Asian Lady Beetle is native to Japan. This lady beetle was first discovered in Louisiana in 1988, and it has been speculated that these beetles entered the United States via an Asian airfreight that was docked in New Orleans. Since then the Harlequins have invaded New York, South America, Canada, Europe and have spread to South Africa as well, where they were discovered by Dr. Goddy Prinsloo of the ARC-Small Grain Institute in 2004.
The number of these invaders has been gradually increasing, invading every habitat they come across. They are classified as a “neozoon”; a biological term for species that invade new habitats and ecosystems.
Scientists from the University of Giessen and the Max Planck Institute for Chemical Ecology (MPI CE) in Jena, Germany, have now established why this beetle has been so successful in invading countries all over the world; its body fluid – the hemolymph – contains microsporidia, a fungus which inflicts substantial damage to their prey. Although the Harlequin is a carrier of this fungus, it does not affect them, but it can prove fatal to those insects on which they prey.
One should be careful when handling these beetles; they show their true colours – or should we say, their ‘darker’ side – by excreting a foul-smelling toxic fluid from their leg joints as a defense mechanism against predators. Not only are the Harlequins a nuisance, but cause serious allergic reactions in humans, such as asthma and eye irritation.
Harlequins are tree-dwelling beetles. They live in forests and also inhabit agricultural crops such as roses, soybeans, tobacco and corn. During the autumn season these “bio killers” invade homes, sheds and buildings for overwintering spots. They enjoy illuminated surfaces and congregate in attics, wall cracks and crevices as well as windows and light fixtures that receive afternoon sunlight. To prevent their entry one can seal cracks around doors, windows and utility pipes with silicone. You can also mount insect screening (5-mesh should be sufficient) over attic and exhaust vents to prevent them from entering your home. One can remove these critters with a broom or vacuum cleaner and deposit them in a covered area away from your home – you don’t want them wandering back indoors! Be careful in handling them, as their bodily fluids can leave stains on walls and fabrics, not to mention being revoltingly smelly!
It is best not to kill these lady beetles. Although we might have a love-hate relationship with them, you might need them later on in the season to control pesky aphids in your veggie garden!