Oct. 17, 2007
By Janelle Huelsman
The beetles are coming! The beetles are coming!
With the arrival of fall and cooler temperatures, Asian lady beetles soon will invade the Ohio University campus and your home. Small comfort that they are in fact biologically beneficial.
The species originally was introduced to the United States for its ability to control pests, according to Kim Cuddington, associate professor of biological sciences.
Cuddington is actually an expert on ladybugs, which have had their reputation somewhat besmirched by the look-alike Asian beetle. She knows a fair amount about the latter, however.
Similar to ladybugs, the multicolored Asian beetles feed on aphids and other agricultural pests. But now they have become pests in their own right -- to humans, anyway.
The first beetles were imported from Asia by the U.S. government in the early 20th century as part of an effort to naturally control insect pests in trees. Although they didn't solve the problem, and most of the beetles disappeared, the U.S. Department of Agriculture's Agricultural Research Service introduced the bugs once more in the 1980s.
In the most recent release, the service turned the beetles loose across the East Coast and the Midwest, and eventually across the Northwest. This time, the beetles, like an insect version of kudzu, multiplied unchecked.
The beetles' beauty is that they feed on pest species such as aphids, which are harmful to fruit crops and other garden plants. Some scientists suggest that the beetles are able to consume about 60 aphids a day, according to Cuddington.
Although the beetles have been in southeastern Ohio all year, most people will not notice them until mid-October, when temperatures become cooler. The beetles often are found in the smallest cracks and crevices of buildings, because they are seeking a warm place to winter.
"They tend to congregate around windows and window sills, but we find them anywhere and everywhere, and a lot of times it's in the smallest of places," said Steve Mack, director of buildings and grounds services for the university, whose division deals with cleaning up after them every year.
As irritating as they become, the beetles do not cause any structural damage or harm people.
"During the winter, the insects do not eat, they do not bore holes and they do not transmit diseases," Cuddington said.
That doesn't mean they aren't ornery. Though an uncommon occurrence, they might bite like any wild creature if you aggravate them, Cuddington says. And then there's the smell and yellow ooze that is certainly potent if not perilous. It's a defense mechanism called "reflex bleeding," meant to repel potential predators.
They're also photopositive, meaning they are attracted to light. Cuddington said this is why they swarm on light-colored homes, congregate on the south side of buildings or buzz around your reading lamp at night.
They also are difficult to beat. The beetles multiply rapidly and stick around for 30 to 90 days or longer.
Both Cuddington and Mack said the best way to rid a home of the Asian beetles is to use a vacuum. To help prevent entry, Cuddington suggests caulking cracks and entranceways on the exterior of a home or building and locking down windows, although anyone who has tried that method knows it to be only somewhat satisfactory.
Some sources recommend spraying pesticides such as pyrethrins or pyrethroids or compounds such as menthol and camphor, but Cuddington believes they may do very little to deter or exterminate the beetles and can instead have environmental consequences.
"I don't recommend (chemical spraying)," she said. "And there is very little anecdotal evidence that menthol or camphor will repel the beetles."
The Ohio State University Extension Service agrees. Its fact sheet on Asian lady beetles says the chemical sprays likely will have no effect and can kill helpful insects that otherwise would curb infestations of other pests.
Whatever the choice for dealing with the beetles, there may be good news this season. According to the Athens County Extension Office, entomologists now think that the drought may have taken a toll on the Asian lady beetle population. Chances are there will be lady beetles around, but their numbers may be reduced.