Aphids put city in sticky situation

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This article was published 19/08/2014 (4172 days ago), so information in it may no longer be current.

If your car is covered in a thick coat of a translucent, sugary substance, congratulations: You now know how to identify aphid excrement.

The sticky stuff all over Winnipeg roads, vehicles and other surfaces this week is honeydew, a substance excreted by the small, green soft-bodied insects known as aphids.

“It’s just a byproduct of the fact they eat plant sap and plant sap has sugars in it. They extract as much sugar as they can, but they can’t get all of it,” said Rob Anderson, a University of Winnipeg biologist and insect expert.

Along with making cars sticky and increasing road traction for cyclists, honeydew serves as a food source for other insects. There are ants that actually protect aphids from predators, just to ensure access to the nutritious poop.

Honeydew also is an energy source for mosquitoes, who consume the sugars in order to fly. “That’s a good reason for people to hate aphids,” Anderson joked.

Aphids are far more of a threat to food crops such as potatoes and tomatoes, which can be infected by plant viruses carried in aphid saliva, Anderson said.

Trees suffering from large infestations can be seriously weakened by aphids, added Taz Stuart, the former city entomologist who now serves as director of technical operations for Poulin’s.

Stuart said aphids can be removed from trees with high-powered hoses. There are also soaps that can dry out the soft-bodied insects or permethrin-based pesticides that can outright kill them, he added.

Any anti-aphid treatment, however, will likely be effective for only several days, as the bugs develop inside folded-over leaves, where they are protected from water, soap or pesticides, Stuart said.

The recent heat has provided good conditions for aphid development, Stuart said. Like most insects in southern Manitoba, they have emerged later than usual due to the cool spring, Anderson added.

Aphid populations usually build up in the late summer before the insects disperse from trees and find somewhere to spend the winter without freezing, Anderson said.

The honeydew season, like everything else summer-related in Winnipeg, just doesn’t last that long.

bartley.kives@freepress.mb.ca