The Village of Mount Prospect has received reports from residents noticing a sticky substance and dark, soot-like residue accumulating on trees, outdoor surfaces, vehicles, and homes throughout the community in recent weeks. The Village’s Public Works Department – Forestry Division has investigated these reports and determined the cause to be Maple Scale, a common insect pest affecting maple and other tree species.

Maple scale insects are small, sap-feeding insects that attach themselves to tree branches and leaves. While often difficult to detect due to their size and protective waxy coating, these insects can become noticeable when populations increase. Maple scale is commonly found on maple species but may also affect other hardwood trees.

As part of their feeding process, maple scale insects produce a sugary waste known as honeydew. This sticky substance falls onto surfaces below, including leaves, sidewalks, vehicles, decks, and outdoor furniture. Residents may notice a shiny or tacky coating forming quickly, especially during periods of high insect activity.

The black, soot-like residue observed by residents is likely sooty mold, a fungus that grows on surfaces coated with honeydew. While sooty mold does not directly harm most surfaces, it can reduce sunlight reaching tree leaves, potentially stressing trees and causing premature leaf drop. The mold can also reappear quickly if honeydew continues to accumulate.

Village arborists note that maple scale populations can fluctuate from year to year. While typically considered a minor pest, periodic population surges can occur. Environmental factors such as mild winters and favorable growing conditions can contribute to increased insect activity, making honeydew and sooty mold more noticeable across the community.

To clean affected surfaces, residents are encouraged to:

• Use gentle cleaning methods such as water, mild soap, or manufacturer-recommended products
• Review environmentally safer cleaning options through the U.S. Environmental Protection Agency’s Safer Choice program
• Follow manufacturer guidance for cleaning specific materials to avoid damage

For trees on private property, residents may wish to consult with a licensed arborist or local nursery for evaluation and potential treatment options. Treatment timing is important for effectiveness, and professionals can provide guidance specific to each situation.

The Village of Mount Prospect appreciates the community’s feedback and vigilance in reporting these concerns. Staff will continue monitoring conditions and coordinating with local and regional partners as needed.

For additional information or questions regarding maple scale or tree care, please contact the Public Works Department – Forestry Division at  847-870-5640.