Timothy J. Gibb, Extension Entomologist

PURDUE UNIVERSITY COOPERATIVE EXTENSION SERVICE  WEST LAFAYETTE, IN 47907 http://www.entm.purdue.edu/entomology/ext/targets/publicat.htm Department of Entomology E-214

Asian lady beetles are attracted to:  light-colored buildings and  highly illuminated or southwest facing sides buildings close to trees or woods. 

(Click enlarge picture) Historically, lady beetles or ladybugs have always been looked upon as beneficial insects, worthy of protection. Their presence is often a sign of good luck because they feed on many serious plant pests, and, in some cases, they have completely controlled certain pest outbreaks. Recently, however, homeowners have had to reassess ladybugs favorable reputation. With the appearance of literally thousands of lady beetles inside a home or garage during late fall or winter, the words “beneficial”, “conservation” and “protection” seem to be the last that come to mind. Pest control operators and university extension personnel have also been sent reeling. How can these insects not be a pest when complaints come in by the bucket load and accounts are canceled because of lack of control? What is the explanation for this new problem? What is to be expected? What can be done?

Not All Ladybugs Are Created Equal Before we begin to answer these questions, it is important to understand the origin of this particular problem. Many different species of ladybugs occur throughout the world, and, although they have many characteristics in common, they are not all identical. For example, all ladybugs feed on small insects, such as aphids or scales, that they capture on plants. The fact that they feed on these potential pests is why ladybugs are considered beneficial. Protecting them or even purchasing and releasing certain species in high numbers to augment natural populations will enhance existing biological control processes. Although general body shape is usually similar, there are vast differences in size and coloration between ladybug species. Even more important is the fact that subtle differences in behavior also occur between species. In fact, it is one such behavioral difference that makes one ladybug, commonly called the Asian lady beetle, a pest as well as a beneficial insect. The difference? The Asian lady beetle’s unusual over wintering habit. Asian lady beetles congregate in large numbers during the late fall rather than disperse to over winter individually under bark or in leaf litter, as do most lady beetles. Asian lady beetles prefer to cluster on the sides of homes and other buildings, eventually working their way into the building through small cracks or crevices, or natural breaks in the window panes, door jams or foundations as the temperatures decrease. Once inside the building, they essentially laze about in a hibernation-like mode, neither eating nor moving much until the first warm days of late winter or early spring, when they seem to come to life again and begin crawling about. This is when most homeowners really notice their company. A few found here or there might be tolerable, especially in light of their beneficial reputation out-of-doors, but when clusters of several hundred to thousands appear in a living room, bedroom, or kitchen, it is hard not to grumble.

Why My Home? The Asian lady beetle spends a majority of its active life feeding high in trees. In late fall, when it begins to migrate, it flies well above the tree tops until it zeros in on a clustering site below. Beetles tend to be attracted to lighter colored buildings and especially to those that are illuminated by the sun. For this reason, beetles usually choose the southwest facing sides of light-colored buildings close to wooded areas. Darker colors or buildings in the shade are less likely to have problems. Once several beetles have settled on a suitable site, they probably release a chemical cue which attracts even more beetles. 

Good News and Bad News The good news is that when Asian lady beetles occur in the home, they are really only a “pest by their presence.” They do not feed on or damage anything in the home. They do not bite people or pets, do not infest stored food and do not destroy household furnishings. Their presence is simply a nuisance most people would rather do without. After spending the winter months tucked away in a wall void or other secluded place, they have simply forgotten how they got in. When they become active in the late winter, they often find themselves inside the home rather than outside. At this time they are merely looking for a way to escape to the out-of-doors. The best suggestion is to help them in their quest by sweeping them up and depositing them outside if possible. Vacuuming also will work where there are a lot of them; however, be sure to empty the vacuum bag afterwards because live beetles can sometimes find their way out of a vacuum left in the closet. The bad news is that the beetles seldom all become active at exactly the same time. This reawakening may take place over several weeks, depending on temperatures and the size of the population. Removing those that become active every day can become a real chore, especially where populations are high. It may seem like there is an endless population or that they are somehow breeding in the home. Rest assured that they are not and cannot breed inside the home. Sometimes, chemicals can be used to assist homeowners in removing Asian lady beetles. Using chemical sprays or “fogs” labeled for inside the home will kill Asian lady beetles. However, the dead beetles will still have to be removed after they die in conspicuous places. This job can be nearly as disagreeable as removing live beetles. If populations are inside wall voids, false ceilings or other inaccessible places, chemical control becomes difficult. Chemicals sprayed or released inside the home will not penetrate these or other secret hiding places. Asian lady beetles in a home will only die after they become active, enter the living areas and contact the chemical residues. In most circumstances, a combination of several control methods is the best answer to Asian lady beetle problems. Physically removing the beetles as described above with a vacuum or sweeping them out is always a good control method. Sealing them out by caulking cracks and around utility service openings, fixing broken window screens and door jams, plugging cracks in the foundation or roof as well as similar exclusion-type activities will help prevent the lady beetles from entering in the first place. Professional pest controllers can be employed who will use synergized pyrethrins in attic or crawl spaces. However, aerosol type foggers are not recommended in other areas of the home. Using pesticides as a perimeter treatment during late fall will also help prevent beetles from getting into the home initially. Use materials which will leave a long lasting residual. Wettable powders, micro-encapsulated and suspended concentrate formulations seem to work best. On the outside of the home, pest control operators may use long-lasting/rapid knockdown chemicals such as Tempo, Demon, Commodore, Saga or Suspend. Homeowners may use Dursban or Diazinon at rates labeled for “household invading” or “occasional” pests. In either case, the key to control is to apply the chemicals to the outside of the home in October before the beetles enter.

Up Close and Personal Those who really want to know how to identify Asian lady beetles and how to separate them from the rest of the many lady beetles, must get up close and personal with them. Identification would be easy if the Asian lady beetle had a consistent color pattern or number of spots that would separate it from all other lady beetles. Unfortunately, it does not. Different color variations, from yellow to red and every shade in between, can be found within a single handful of beetles. Many of these beetles have black spots, some have many, some have few and some have no spots at all. The Asian lady beetle looks like most other lady beetles (oval, convex, approximately 1/3 inch in length), but the most common identifying character that Asian lady beetles share is a black ‘M’ inscribed on their thorax, just above the wing covers. Some M’s are darker and more apparent than others, but their presence is almost always a good diagnostic tool. Note the location of the M in the diagram on the front page.

One of the reasons that scientists use Latin names to describe life forms is to prevent such confusion. They have given the name Harmonia axyridis to the species of beetle that we are discussing. This way, scientists can be sure they are talking about the same species, regardless of location or the local common name.  

Here to Stay The Asian lady beetle has an interesting genealogical story. It is very common in eastern Asia, where it is thought to have originated. It is a very good predator against aphids and scale insects in the forested areas and orchards there. It is also quite weather hardy and is highly reproductive. That is why scientists collected it and introduced it to the United States for the control of orchard and field crop pests. Introductions into California, Texas, Mississippi, Louisiana, Maryland, Connecticut, Georgia, Ohio, Pennsylvania and Washington have all been recorded. Since these initial releases, the beetle has done a very good job of spreading and currently can be found in nearly all of the United States and much of Canada. There is no doubt that Asian lady beetles are helping to control aphid and scale infestations. What is unclear is whether this benefit outweighs the negative aspects of its over wintering behavior. The important point, however, is that the beetle is here and here to stay.  

What Is the Future of This Beetle? Because the Asian lady beetle is here to stay, we must learn what we can in order to live with it. Like any other newly introduced animal, populations will probably gradually subside over the next few years. Experience has taught us that populations of any newly introduced insect, pest or beneficial, increase very quickly in the first few years after introduction. This is due, in part, to the fact that, while the insect was introduced from a foreign country, the naturally occurring diseases, parasites and predators that keep it in check were not. These usually follow any new introduction, but there may be a lag time of several years. What this may mean is that even though the beetle is increasing in numbers now, once populations of natural enemies have time to build up, we should see the beetle numbers level off and then gradually begin to decline over time. 

Bugaboo^®  Pest Control, LLC doityou

Ant exterminate, odorous house ant exterminate, Carpet beetles exterminate, caterpillars exterminate, catapillers exterminate, centipedes exterminate, crazy ant exterminate, dursban exterminate, entomology exterminate, flea exterminate, flies exterminate, bebbugs exterminate, bed-bugs exterminate, bed bugs exterminate, hornets exterminate, yellowjackets exterminate, wasps exterminate, cloth moth exterminate, colthes moth extSerminate, clothing moth exterminate, clovermite exterminate, clover-mite exterminate, clover might exterminate, cricket exterminate, food bugs exterminate, food and pantry bugs exterminate, fruitfly exterminate, fruit flies exterminate, fruit-flies exterminate, head-lice exterminate, head lice exterminate, hobo exterminate, lady bug exterminate, lady-bug exterminate, lady-bug exterminate, little tiny ants exterminate, sugar ants exterminate, piss ants exterminate, mole exterminate, mole information exterminate, lice exterminate, lyme disease exterminate, lime disease exterminate, sowbugs exterminate, sow-bugs exterminate, sow bugs exterminate, Anobiid exterminate, Powderpost Beetles exterminate, Coleoptera exterminate, Anobium punctatum exterminate, Xestobium rufovillosum exterminate, parasites exterminate, Brownbanded exterminate, American cockroach exterminate, Oriental cockroach exterminate, German cockroach exterminate, mosquitoes exterminate, Diptera exterminate, Culicidae exterminate, rorway rats exterminate, roof rats exterminate, beetles exterminate, beatles exterminate,

rselfpestcontrol do-it-yourself-pest-control do_it_yourself_pest_control doyourownpestcontrol do-your-own-pest-control do_your_own_pest_control pestcontrolsupplies pest-control-supplies  pest_control_supplies bugoutlet bug-outlet bug_outlet pestproducts pest-products pest_products victorpest victor_pest victor-pest orkin terminex amazonpest
Copyright © 2001 [Alan Luke]. All rights reserved.
Revised: 05/11/08. Home