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City deploys aphid-eaters

City staffers hope a team of ladybugs will help them gobble up St. Albert's aphid problem. Hordes of black aphids have descended on St. Albert in recent weeks, turning branches black, flying in faces and secreting honeydew.
A ladybug rests on a Canada thistle that is heavily infested with aphids. Wet weather has contributed to a plague of aphids in St. Albert this month. City staffers deployed 1
A ladybug rests on a Canada thistle that is heavily infested with aphids. Wet weather has contributed to a plague of aphids in St. Albert this month. City staffers deployed 1

City staffers hope a team of ladybugs will help them gobble up St. Albert's aphid problem.

Hordes of black aphids have descended on St. Albert in recent weeks, turning branches black, flying in faces and secreting honeydew.

The pests were pretty noticeable around St. Albert Place, says city parks foreman Kevin Veenstra, where they were sucking the life out of shrub beds. Public works staff deployed 1,000 hungry ladybugs in those infested shrubs on Wednesday in hopes that they will eat the pests.

"As they hatch, the larvae will take care of the aphids," Veenstra says.

This was the first time that the city had used beneficial bugs to try and control pests, he added.

It's an interesting idea, says Jim Hole of Hole's Greenhouses, but it might not work.

"The issue with ladybugs is they tend to really disperse," he says, and there's no way to ensure they'll stick around to defend the shrubs. "It could be a bit of a shotgun approach."

They're everywhere!

Aphids are small oval-shaped bugs, usually black and winged, that suck sap from plants. They're a nuisance, Hole says, as they excrete the sugar from sap, spreading honeydew and attracting ants.

Female aphids are born pregnant and can bear live young, he continues, which lets them build up their numbers super-fast — one female can theoretically have 600 billion descendents in a season.

Peter Heule, who runs the Bug Room at the Royal Alberta Museum, says he's been getting plenty of calls about aphids as of late.

"I think I get more [aphids] on me than mosquitoes nowadays," he says.

The reason for all the bugs is the wet weather, he explains. Rain means more plants and more plant juice for the bugs to suck, which leads to more bugs.

"We're also seeing a lot of aphids flying," he continues. Plants start shipping nutrients into their roots at this time of year, making them less attractive to aphids. The bugs sense this change, and start producing winged males and females to spread to other plants. "This is now the aphids saying, 'OK, go forth and multiply.'"

Ladybugs to the rescue?

The city ordered 1,000 ladybeetles from an Ontario company for about $23 earlier this week, Veenstra says. "You get a bag full of ladybugs," he says, and you spread them where you want them.

Ladybugs eat aphids their entire lives, Heule says. They start off as eggs that hatch into larvae, which are often black, orange and gray. Eventually, they turn into stationary pupae and emerge as beetles.

The ones St. Albert has used are convergent ladybeetles, he continues — a native species found throughout Canada. These creatures are smaller, more elliptical and more orange than the invasive seven-spot ladybug, which is far more common.

"If [St. Albert] is using a native species," Heule says, "I've got to give [them] a pat on the back."

Researchers suspect that introduced aphid-eaters such as the seven-spot are crowding out native ladybugs, although recent research by naturalist John Acorn suggests this may not be the case.

Ladybugs are thought of as the premiere aphid fighters around, Hole says, but they're not — he's used them in his greenhouse and found that parasitic wasps were far more effective. "[The ladybugs] just look for ways to get out." The city should monitor these bugs closely to track their effectiveness, he says.

Ladybugs will scatter quickly unless they find aphids right away, Heule says, but you can use aphid magnets such as lupines to keep them in place. While ladybugs are voracious, St. Albert residents shouldn't expect them to eat all their aphids — if they did, the ladybugs would starve and die.

The aphid problem should settle down soon as the bugs lay their eggs for the year, Heule predicts. "I can't imagine it'll last more than a week or two."




Kevin Ma

About the Author: Kevin Ma

Kevin Ma joined the St. Albert Gazette in 2006. He writes about Sturgeon County, education, the environment, agriculture, science and aboriginal affairs. He also contributes features, photographs and video.
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