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Aphids are being a real nuisance in city trees secreting a sap-like substance resulting in sticky situations on cars, sidewalks and anything else in their path. Submitted photo

Aphids causing sticky situation

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News Fargo,North Dakota 58102
West Fargo Pioneer
Aphids causing sticky situation
Fargo North Dakota 101 5th Street North 58102

If you have trees on your property this year that are releasing an overabundance of a sap like substance and you are wondering why, aphids are the culprit, according to West Fargo City Forester Yvette Gehrke.


Aphids are small pear-shaped, soft-bodied insects that come in many different colors depending on the species. The pesky insect likes to pierce the leaves of the trees with their mouths and suck the fluid out causing the leaves to curl and look puckered or distorted.

In doing so, they consume an excess of sap to satisfy their nutritional requirements which is expelled as honeydew in large volumes that fall abundantly.

The honeydew is very sticky in nature often described as a "clear, sticky liquid raining from trees." It coats bark, leaves, and objects beneath the plant and is easily seen on car windshields and lawn furniture, and can be difficult to remove.

Gehrke said she has been receiving several calls from residents about the sticky situation that appears to be emanating mainly from ash trees all around town including areas to the south in Eagle Run.

The aphids seem to like ash trees but can also be found on rose, oak, maple, willow and fruit trees and tend to cluster on unopened flower buds, the underside of young leaves, and developing stems.

Gehrke said the last time there were aphid numbers this high was about twenty years ago in the early 90s. "Every year there are aphids out there but this year's weather conditions were extremely favorable to a high population. Everything lined up perfectly for their growth cycle with the mild winter and early spring."

Since they repopulate quickly, aphid counts can build to enormous levels in a very short time. Consequently, Gehrke said they will be around all summer.

"The good news is aphids will not do harm to mature trees," Gehrke said. "They are just messy and look terrible." However, it's a different story for the younger trees which could be harmed by the over-abundance.

Most infestations can be controlled or eliminated by using a garden hose and spraying the aphids out of the trees or by using newer and safer insecticides.

The recent heavy rainfalls have been somewhat helpful with lessening the numbers, helping wash down the residue. Gehrke said if residents do opt for insecticide treatment, they should remember that this method could also eliminate other beneficial insects present on the trees.

Gehrke noted Lady Bird Beetles, more commonly known as the Lady Bug, are natural predators to aphids. They can be ordered on line and released into the trees to take care of the aphid problem.

Anyone with questions or wishing more information can call Gehrke at the West Fargo Public Works Department, 701-433-5408.