Manitoba

Hey Winnipeg, notice all that sticky goo? It's honeydew from aphid poo

If you're stuck for an answer about that tacky coating on vehicles, sidewalks, roads, and trees around Winnipeg right now, we're here for you. Simply put, it's poo.

Aphids reproduce quickly, generating a new population approximately every 7 days

Aphids, the white specks seen here, have coated the leaves in a sticky varnish and left a pool of honeydew. (Walther Bernal/CBC)

If you're stuck for an answer about that tacky coating on vehicles, sidewalks, roads, and trees around Winnipeg, we're here for you.

Simply put, it's insect poo.

It's the work of aphids (also known as plant lice), small insects that suck sap from tree leaves like someone drowning their sorrows at a bar.

They then excrete honeydew — a sticky liquid that drips down from their lofty lounge, coating whatever is below. It creates syrupy streaks and droplets on vehicles, and pools in the curled basin of leaves.

When someone walks over the tacky ground from the aphid excretion, it makes a sound like packing tape being peeled back. (Walther Bernal/CBC)

"We've had to go to the car wash quite a few times," said Shauna MacRae, a Wolseley area resident who's SUV has been hit by the goo.

On the pavement, the honeydew shows up as a discoloured, darker area that makes a sound like packing tape being peeled back when a rubber-soled shoe steps on it or tires roll across.

It's the sort of stickiness you get when a Popsicle melts between your fingers — and it's just as sweet, according to Ken Nawolsky, superintendent of insect control for the City of Winnipeg.

The sugary substance is attractive to bees, wasps and even ants.

"Often, when there's a large population of aphids, you may see ants crawling up the tree. The ants actually will go suck the honeydew from the aphids and protect the aphids from natural predators," Nawolsky said.

"It's quite a remarkable system."

Aphid honeydew is seen as darker, discoloured areas on a sidewalk near the CBC building in downtown Winnipeg. (Walther Bernal/CBC)

It's normal to get aphids at this point in the season, but this year you might be noticing more of them because the extended warm, dry weather has allowed their population to soar, he said.

And there's not much you can do about it. They generate a new population approximately every seven days, Nawolsky said.

"There's really no control mechanism for aphids because they reproduce so quickly. If you treat one area [of the city], aphids from other parts of the city will just re-infest it," he said.

"And because they have so many generations, if you were to apply any kind of product, they build up resistance."

University of Manitoba entomology instructor Jordan Bannerman added the bugs are self-mating machines that don't need a partner in the summer months to reproduce.

"That's why we can see or can see such high aphid numbers in the summer is because they're essentially just cloning themselves."

Ladybugs like to chow down on aphids but there's just not enough of them to make a big dent, Nawolsky said.

"They can only eat so many of them."

One thing that could help is a really strong thunderstorm with intense rain, which will cause a lot of aphids to fall to the ground and be washed away. Typically, the rain would also clean the sticky pavement, but it's been so dry that hasn't happened this year, Nawolsky said.

"We're supposed to be getting some [rain] later tonight, so it will be a little bit better coming up," he said.

Shauna MacRae lives in Wolseley where aphid poo has been a problem this summer. (Walther Bernal/CBC)

In the meantime, it's a nuisance we all just need to endure. There's no harm from the aphid assault, which could potentially last until the end of August.

"Your trees won't die or anything, it's just that the conditions are perfect for a very high population this year," Nawolsky said.

On the positive side, the dry weather has left the city with a dearth of mosquitoes.

"So far, so good," said Nawolsky. "Whenever it does rain, there's always mosquitoes hatching but we've been able to control [the population].

"Our average [trap count currently] is three, which is remarkably low."

Sticky spots on a car window are the syrupy droppings from aphids. (Meaghan Ketcheson/CBC)

His department is carefully watching the weather system heading into the province on Monday to see how much rain develops. While it will wash away some aphids, it will also create breeding opportunities for mosquitoes.

"The [forecasting] models are very mixed, anywhere from 15 millimetres to 50 millimetres," he said.

"As long as we don't get those super cells, then we should be in really great shape to have low population of mosquitoes continuing for the next few weeks."

About the Author

Darren Bernhardt

Reporter/Editor

Darren Bernhardt spent the first dozen years of his journalism career in newspapers, first at the Regina Leader-Post then the Saskatoon StarPhoenix. He has been with CBC Manitoba since 2009 and specializes in offbeat and local history stories and features. Story idea? Email: darren.bernhardt@cbc.ca

With files from Meaghan Ketcheson and Austin Grabish

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