How ’bout Them Lady Bugs?

by Robert Michael Pyle October 26, 2011

If you have an older house, not necessarily airtight, you know how it is around this time of year: every time the sun shines and the air warms up, scads of ladybugs swarm and crawl around your windows, trying to get out. Then when it cools down again, they cluster in the corners, ready crawl forth and drop into your tea, stink up your vacuum bag, or give you a nip in a tender place. So-called ladybugs, cute and roly-poly, have always been among the most beloved of insects (which isn’t saying much). But these days, the great abundance of ladybird beetles (= ladybugs) in many homes and buildings (including the Grange Hall) has become a real concern to many people, and a problem for those who have to live with them and clean them up. So here are a few facts about these less-than-welcome insects–their origins, their behavior, and what can be done about them.

The insect involved looks like a ladybug, but is very variable, with no spots or many, pale or deep orange or even all black with two fire-engine red spots. In fact, it is neither a native species nor a real ladybug (genus Coccinella). Known as the Asian or variable ladybird (Harmonia axyridis), this insect was intentionally introduced from East Asia and widely sold to gardeners and farmers to fight aphids. They arrived here in the Northwest in the early 1990s.They have become important bio-controls for the soybean and pecan crops in the Midwest and South. But unlike native ladybugs, they don’t just stick around and do the job. Instead, in the absence of their own native predators and parasites, they build up in huge numbers over the summer and disperse, probably having an adverse effect on native ladybugs and butterfly eggs and larvae. Then, for the part we hate, they take up winter residence in buildings. They do this because in nature, they hibernate in caves and hollow logs. Our houses make perfect caves for them, so inevitably they come inside and stay for the winter months, before trying to get out and fly away again.

As autumn approaches, the adult beetles leave their summer feeding sites in yards, fields and forests for protected places to spend the winter. Unfortunately, human habitations are one such location. Swarms of lady beetles home in on buildings from September through November, depending on latitude and weather. Incoming flights are heaviest on sunny days following a period of cooler weather, when temperatures return to at least the mid-60s. Once the beetles alight on buildings, they seek out crevices and protected places to spend the winter. They often congregate in attics, wall cavities, crawl spaces, and other protected locations including grooves around window sashes and doorframes, behind fascia boards and exterior siding, and within soffits, crannies, and walls. Just pick something up, and there’s a beetle.

As temperatures warm up in late winter and early spring, the beetles once again become active. This usually occurs first on the sunnier, southwest side of the building. As awakening beetles attempt to escape to the outdoors, some inadvertently wander inward, emerging from behind baseboards, walls, attics, suspended ceilings, and so on. Since the beetles are attracted to light, they are often seen around windows and lamps. Turn on your baseboards to warm up the bedroom on a chilly night? Watch out!

Since the problem has been growing all over the country, a lot of attention has been given to controlling and coping with them. The results are not especially encouraging. Most authorities, including university departments and extension agencies, emphasize two main defenses: sealing the building and vacuuming. The former is obviously impractical for big old buildings like Redmen Hall in Skamokawa, which has a huge challenge with them. . As for vacuuming, most folks already do a great deal of it; but there are some ways to make it more effective and less noxious.

The major complaint for this method is that the beetles become agitated and expel the yellow, foul-smelling defensive repellent, which is then circulated into the air by the vacuum exhaust. And if you don’t empty the bag right away, the beetles just crawl out, or rot and become even more foul-smelling. Experts recommend capturing the beetles inside a knee-high nylon stocking that has been inserted into the extension hose or wand, and secured in place with a rubber band. As soon as the vacuum cleaner is turned off, be sure to remove the stocking so that the captured beetles cannot escape. As you remove it, the rubber band closes around the stocking, effectively “bagging” the lady beetles. You then can discard the contents far from your house. This way you will not need to change the bag every time you vacuum.

The temptation is to spray or bug-bomb the ladybugs. But here is what government and university entomologists say about that (and other authorities concur):

Insecticide foggers, ‘bug bombs’, or sprays are generally not recommended for eliminating beetles indoors. Insecticides applied indoors for lady beetles tend to be ineffective and may stain or leave unwanted residues on walls, countertops and other surfaces. Attempting to kill beetles hibernating in wall cavities and other protected locations is seldom effective. (USDA)

In an autumn ritual as sure as falling foliage, tens of thousands of Pennsylvanians are locked in battle with ladybugs, beetles and other insect invaders. A specialist in Penn State’s College of Agricultural Sciences says bug sprays won’t win this war. Entomologist Steve Jacobs says homeowners shouldn’t count on pesticides in this annual battle of the bugs. It is possible to have a professional spray the outside of your house, but even then you’re going to have a very, very minimal effect, so it’s probably best not to even bother. It’s better to try to make the house as tight as possible on the exterior, and once they’re on the inside, collect them and dispose of them. (U. Penn.)

The reason sprays and bombs don’t work very well is that the beetles are so tightly secreted, and spread out, that the chemicals don’t reach them in sufficient concentration. To effectively eliminate ladybugs from a big space, you’d need to use a great deal of toxic material. It is particularly pointless to spray in the spring, when all the ladybugs are trying to do is get out of there anyway. By May Day or soon thereafter, they should all be gone or dead.

The only voices in favor of a chemical solution are, not surprisingly, chemical companies, spray manufacturers and sales agents, and exterminators. They are not reliable sources on this issue! Furthermore, their claims of “non-toxic” and “safe” for their products cannot be trusted. Most of the chemicals used against house insects these days are pyrethrum, pyrethrin, and other pyrethroids. These are considered among the safest of insecticides, but safety is relative. Here is a list of the dangers of these chemicals, from a non-industry, public health source:

Effects of Pyrethroids on Humans: Inhalation: coughing, wheezing, shortness of breath, runny or stuffy nose, chest pain, or difficulty breathing. Skin contact: rash, itching, or blisters. Long term effects: disrupts the endocrine system by mimicking the female hormone, estrogen, thus causing excessive estrogen levels in females. In human males, its estrogenizing (feminizing) effects include lowered sperm counts. In both, it can lead to the abnormal growth of breast tissue, leading to development of breasts in males and cancerous breast tissue in both male and females. Neurotoxic effects include: tremors, uncoordination, elevated body temperature, increased aggressive behavior, and disruption of learning. Laboratory tests suggest that permethrin is more acutely toxic to children than to adults. Other: A known carcinogen. There is evidence that pyrethroids harm the thyroid gland. Causes chromosomal damage in hamsters and mice; deformities in amphibians; blood abnormalities in birds.

I know this isn’t very encouraging, since you probably already vacuum like crazy, you cannot caulk the whole place, and it is inadvisable to expose yourself and your family to these chemicals, as well as largely ineffective. So here are at least a few positive suggestions:

1) Try the tip given above to save your vacuums and produce less smell and staining.

2) If windows on the south walls can be opened on sunnier days in spring and closed at night, you will get rid of more beetles faster. The more your home can be shut up tight in the fall and opened up wide on warmer days in spring, the fewer ladybirds will get in, and the faster they will go out.

3) Live and let live, as much as possible. The hungry ladybugs eat clothes moth larvae, aphids, whiteflies, and other houseplant pests, and they can be fairly entertaining to watch–at least as much as most TV.

To read more about Asian ladybird beetles, see:

I hope these comments will be helpful. I recommend you also read the section about ladybugs in our house in my book, Sky Time in Gray’s River (pages 161-162 + a note on p. 88), just so you know that Thea and I really do share your pain.


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