Heat made aphids stick around longer

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This article was published 17/08/2021 (1664 days ago), so information in it may no longer be current.

WINNIPEG’S drought has created an unusually sticky situation on streets and sidewalks, by allowing aphid droppings to build up for much longer than usual.

In a normal year, rain tends to wash away the goo often and make it far less noticeable. However, last month marked the driest July in nearly 150 years, when Winnipeg had just 8.5 millimetres of rainfall.

As a result, the natural cleaning effect of precipitation didn’t take place for several weeks.

“In a normal year, we would get a rainfall every week or so and the rain would be enough to wash off the aphid droppings. But we basically went almost two months (this year) without rainfall, so it just built up more. With it being hot, it just made it that much more sticky,” said David Wade, a surveillance program co-ordinator with the city’s insect control branch.

And just as the droppings stuck around, persistent hot temperatures created the perfect conditions to support a larger aphid population, further increasing the buildup.

“The aphids do have multiple generations in a year and the hotter it is, the more generations they will have,” said Wade.

While recent rain has finally helped wash away the goo, which consists mostly of sugar and water, Wade noted the buildup could become more common in the future.

“If, through climate change, Winnipeg receives less rain and hotter temperatures, then, yes, aphids would be more noticeable in the future or continue to be as noticeable as they were this year,” he said.

Before the recent moisture, the city received some complaints about excess aphid residue, he said. While many Winnipeggers believed the sticky layer that built up on vehicles and paths was aphid poo, that’s technically not the case, since it’s excreted through a tube in the bug’s abdominal area, said Wade.

The city doesn’t currently treat trees to rid them of aphids. Its website states that’s because there isn’t an effective large-scale treatment for aphid control because the bug reproduces very quickly. The critters also tend to cause limited harm to trees, the city notes.

Aphids are expected to remain noticeable until the end of the month.

joyanne.pursaga@freepress.mb.ca

Twitter: @joyanne.pursaga