Friday, April 2, 2010

Invasion-The Asian Lady Beetles Are Here!

I spent an hour yesterday afternoon attacking a bug orgy on our basement bathroom window with the vacuum cleaner. The Asian Lady Beetles are back and this year they are worse than ever before. The little 2' X 3' south facing window on the west side of the house was two layers deep in these little boogers. The warm bright window attracted them in droves and they, evidently, took the opportunity to do some spring mating.

I don't know about other areas of the country but Asian Lady Beetles (Harmonia axyridis) are a huge problem here in the Midwest. I don't remember ever seeing them in Texas so maybe the climate is wrong for them there. Here in Iowa, they are pervasive pests that insist upon coming into your home for in the fall looking for a good place to hibernate. In the spring, they wake up when temperatures get to about 50F and cluster around doors and windows looking for a way to go back outside, though they never seem to find that open window or door through which to make their escape. The net results are window jams and floors littered with bug carcasses such that even vacuuming once per day only barely keeps the problem in check. That in and of itself is irritating enough, but tack on the smell and little orange stains that their bodies generate as a defense mechanism and in death and you have a problem that will drive you distracted insanity.

The Asian Lady Beetle is native to eastern Asia through Russia, south to the Himalayas and east to the Pacific and Japan. It is a voracious predator and is considered to be a biocontrol for aphids and scale insects. As such, it has been intentionally introduced outside of its native range to the USA, a good chunk of Europe, and other non-native areas of Asia. It is not entirely clear when or how Asian Lady Beetles were first introduced to the USA. There are records of unsuccessful attempts to establish this insect in the USA as far back as 1916. In the early 1980's the United States Department of Agriculture (USDA) once again began introducing the insect to the southeast USA to combat a significant aphids problem troubling pecan growers. According to the USDA, these attempt were also unsuccessful. However, in 1988, an established population was discovered near New Orleans. There is some dispute as to whether this colony was a result of the USDA's efforts or whether it was accidental introduction due to international shipping and to be honest it really does not matter. They are here now and with no natural predators in the USA, these bugs have spread very quickly. By 2000, they were common in the Midwest. Reportedly, Asian Lady Beetles feed heavily on soybean aphids (an accidental import from China), supposedly saving farmers from a plague of aphids in 2001. Of interest, these bugs are omnivorous. They prey heavily on other bugs (including native ladybugs) but as the growing season wanes in the late summer/early fall, so does the availability of its prey. Thus, it is not uncommon to find these beetles looking for sugar-laden fruit at that time of year.

Harmonia axyridis looks much like a "typical" native lady bug in shape and size. It occurs in three main colors: yellow, red, or orange with black spots (succinea), which are the most common in Iowa; black with four red spots (spectabilis); and black with two red spots (conspicua). Numerous intermediate and divergent forms have also been recorded. It often has white markings (typically "M" shaped) just behind the head and brown or reddish legs. All lady bugs release a defensive chemical (isopropyl methoxy pyrazine) when agitated or dying. However, Asian Lady Beetles release it in much higher concentrations than do natives. This liquid has a bad odor and causes a yellow-orange stain. Asian Lady Bugs are also more prone to biting, which typically leaves small irritated welt (classic bug bite). However, some people (such as DH and myself) are allergic to these critters, with reactions ranging from itching, light rashes, watery eyes, a perpetually running nose, upper respiratory symptoms, and, in some cases, persistent asthma.

There is not much that can be done by way of controlling these infernal pests. The recommendations are to seal up your house (practically impossible) and to vacuum up the ones that do get inside. Because they are considered beneficial insects, the recommendation is to suck them into a homemade pantyhose "filter" so that you can relocate them outside. However, I figure that the population of these things is large enough to withstand loosing the ones that invade my house. Adding kitty litter deodorizer to the vacuum's filter bag helps abate the stink. I did get a light trap to try in the basement bathroom (the primary congregation point in our house) and it works OK so long as you have some ladybug pheromone lure to add to the trap.

So every spring, I break out the kitty litter deodorizer, start my Zyrtec regimen, set up the light trap, and make sure that the Hoover is ready for battle. Then I patrol the house almost daily, cursing and cackling as I suck up the stinky little blighters as revenge for their invasion of my home.

1 comment:

  1. We've got them here, too, but not near as bad as you guys do it seems. I've caught a few of them in the house over the past couple of days. Good luck....