Homeowners were aghast last fall when nightmarish numbers of Asian lady beetles descended on their doorsteps, then made themselves right at home — indoors.
These bugs “completely enveloped” their new home one day last September, recalls Susan Mooney, a retired public health nurse who lives with her husband on a rural acreage near Carman.
“They were all over windows, all over the siding, all over the soffits,” she said. And right away they were crawling throughout their new home too.
“Very quickly it was like an invasion. The ceiling was kind of moving with them,” she said.
She furiously vacuumed every day trying to stay atop of them, to little avail. They abated through the winter somewhat, although the Mooneys often saw a few crawling in the sunroom.
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But as spring advances, so are the lady beetles. They’re now emerging from whatever nooks and crannies they overwintered in and once more they’re dropping from overhead lights and crawling along their floors, she said.
“I can only use a word like infestation and an invasion of our private space inside our home,” said Mooney.
“It makes flies and mosquitoes look tame.”
The Carman-area couple is among many Manitoba homeowners now trying to rid their homes of this most unwelcome of house guests.
Scotti Stephen who lives with her husband in an older farm home in nearby Notre Dame has been doing battle with the ladybug all winter too. Their home was built in 1938 and extensively renovated a half-dozen years ago but the new insulation, siding and windows weren’t enough seal to keep these insects out, she said.
They never put their vacuum away anymore, she said. And she cringes to think what they’d find under that new siding if they removed it to investigate. Friends took some off their own house and found a mass layer of lady beetles beneath.
“They are a royal pain,” she said. “You’re making coffee and boiling the water and they’re in there.”
And what’s next, Stephen now keeps wondering.
“I understand they were brought in to help the farmers,” she said.
“But are we now going to have them all year round?”
That — and what’s to be done about them — are questions regularly put to Manitoba Agriculture entomologist John Gavloski.
“I get lots of calls,” he said. “My job is agriculture but I do get calls from people who complain about them being in their homes and want to know what to do.”
He agrees they can be a nuisance indoors, he said. But he’s at a bit of a loss about what to do about them.
“There isn’t really a lot I can recommend,” he said. “All I can really suggest is to the best of your ability, if you know or can figure out where they’re getting in, to just try to make the house as least accessible to them as you can.”
Gavloski has written extensively about the multicoloured lady beetle, and how its colours, behaviour and big appetite for aphids distinguish it from the other 66 species of lady beetles species found in Manitoba.
This one’s origins are Eastern and Central Asia, and they were purposely released several times in North America as a means of biologically controlling some insects, he explains.
This particular lady beetle has a huge appetite for aphids, eating anywhere from 15 to 112 a day, and that makes them a boon to farmers who can use fewer pesticides to keep the aphids down in their crops.
What the entomologist tells worried housekeepers asking if the worst is yet to come is that one bad year isn’t necessarily followed by another.
Overwintering lady beetles aren’t reproducing inside your home, and what population levels they’ll reach this year will depend entirely on how much food is available.
Last year’s bumper crop of aphids on the province’s expanding acres of soybeans, plus some pea and cereal crops to the west, is what pushed lady beetle numbers skyward in 2017. Dry weather conditions played a role in pushing up aphid numbers.
“It’s food that drives their (lady beetles) populations,” he said. “The numbers we see in 2018 will depend on what the aphid levels are like in 2018.”
And while there’s no way to predict exactly what may occur, aphid outbreaks the likes of last year’s don’t tend to occur two years in a row, he added.
“We’ve never had two consecutive years with very heavy aphid levels in soybeans. That’s not to say it can’t happen but historically it hasn’t.
“There are a lot of lady beetles starting out (the year) because we had a lot overwintering this year in people’s houses and other places,” he continued.
“But how well the new generation does depends on food.”
Spraying for lady beetles — if they’re bad again — isn’t recommended.
“The one exception is those who harvest grapes for wine because they get into grape clusters late in the season and taint the wine. We really don’t recommend spraying for populations of them outdoors because they’re doing good.”
How to keep them there is a question inventors might want to start asking. Window screens or “wove wire” were the innovation that came to the rescue of homeowners plagued by mosquitoes and flies more than a century ago.
There are no public health risks associated with lady beetles, a provincial spokesman said in a written email last week. There is some recent research showing that the odour or stain the beetles emit if they’re disturbed can cause allergies ranging from eye irritations to asthma. Infestation levels “would likely need to be quite high” for that to occur, however.
Lady beetles can also bite when disturbed and “though seldom serious, bites can be disconcerting for those handling these beetles,” the statement said.
Mooney uses the term “unintended negative consequence” to describe the dilemma of an otherwise beneficial insect now becoming a real headache for housekeepers.
“I don’t think anyone anticipated their tenacity and their propensity to invade every space in our houses,” she said.
They’re now talking to their home’s original contractor to see if there’s a way to seal it against a future invasion.
“Those beetles can get into the smallest spaces,” she said. Undoubtedly, the construction industry will be paying more attention to this if the insects remain problematic, she added.
“You’re talking thousands of bugs inside your home. This will have an impact on buildings if this is an ongoing problem.”