Tree sap? Think again


Is your vehicle covered in a sticky glue-type substance? Have you noticed the dark patches on the pavement under large trees or felt your shoes sticking to the sidewalk?

At first, you might think that the trees are sapping, but according to horticulturalist Marci Bomford, the sticky substance is actually coming from aphids. In fact, it’s their poop.

“It may be due to the drier weather this year or perhaps because of the milder temperatures during the winter months that there wasn’t much winter kill of the eggs. As a result, aphids are high in numbers and their only natural predator is lady bugs. And unfortunately, I haven’t seen a lot of lady bugs this year,” said Bomford.

The aphids are feeding on the underside of the leaf on tree sap. The sugar-rich liquid, known as honeydew, is the secretion of the aphids. Once the aphids are done sucking or feeding on all the sap from a tree, they generally move on.

The number of aphids increase rapidly because of asexual reproduction and their ability to lay eggs up to 60 times in their lifecycle.

While Bombford said it doesn’t actually harm older, well established trees, it does stress them somewhat. In order to get rid of the aphids you would have to spray the entire tree, specifically the underside of the leaf, with a liquid insecticide soap. While this may be feasible for smaller trees and shrubs, it’s not always realistic for the towering species like Linden or Elm trees, which seem to be popular with the aphids this year.

With any luck, we’ll start to see more lady bugs real soon so they can help control the aphids and we don’t have to deal with all this sticky poo much longer!