Have you ever parked underneath a tree and returned to find your windshield covered in sticky droplets?
Maybe your patio furniture, sidewalk, deck, or plants underneath the tree feel tacky too.
You may assume the tree is dripping sap, but another substance is often responsible: honeydew.
Honeydew is a sugary liquid produced by certain sap-feeding insects, including aphids and several types of scale insects.
Why Do Insects Produce Honeydew?
Aphids and similar insects feed by inserting specialized mouthparts into plant tissue and consuming fluids.
Plant sap contains large quantities of sugars. The insects process what they need and excrete the excess as a clear, sticky liquid.
That liquid falls onto leaves, branches, vehicles, patios, sidewalks, outdoor furniture, and anything else underneath the tree.
Michigan State University Extension identifies honeydew as a common sign associated with aphids and scale insects on landscape plants.
Why Is My Tree Covered in Black Material?
Honeydew frequently leads to another noticeable problem.
A fungus known as sooty mold can grow on the sugary residue.
Sooty mold often appears as a black coating on leaves, branches, vehicles, or surfaces underneath the tree.
The fungus itself is generally growing on the honeydew rather than directly attacking the tree tissue.
However, extensive coatings on foliage can interfere with light reaching the leaves and make the tree look unhealthy.
Ants Can Be Another Clue
If you see large numbers of ants traveling along the trunk and branches, take a closer look.
Ants are attracted to honeydew because of its sugar content.
In some cases, ants even protect aphid colonies from natural predators because the insects provide a continuing food source.
Seeing ants does not confirm an aphid or scale infestation, but it can provide another useful clue.
Does Honeydew Mean My Tree Is Dying?
Usually, no.
Many trees tolerate low or moderate populations of sap-feeding insects without serious long-term damage.
Natural predators such as lady beetles, lacewings, and parasitic insects may also reduce aphid populations naturally. MSU notes that many aphid problems can decline as beneficial insects catch up with the population.
Heavy infestations, however, can sometimes contribute to leaf curling, yellowing, thinning, or branch decline.
The health of the tree matters too. A tree already weakened by drought, root damage, or disease may respond differently than a healthy tree.
Avoid Treating Before Identifying the Problem
Seeing sticky residue can make homeowners want to immediately spray the tree.
That is not always the best approach.
Broad insecticide applications can also affect beneficial insects that naturally help control pest populations.
The appropriate response depends on the insect, tree species, infestation severity, tree size, time of year, and overall health of the tree.
Correct identification should come first.
Can Honeydew Damage Cars and Outdoor Surfaces?
Honeydew can create an unpleasant sticky coating and attract dirt.
If vehicles or outdoor furniture are underneath an affected tree, regular cleaning can help prevent buildup.
Sooty mold may make the residue darker and more noticeable.
The bigger question is what is producing the honeydew and whether the insect population is affecting the tree.
Look at the Entire Tree
If your tree is producing noticeable honeydew, check for other changes.
Look for:
- Curling leaves
- Yellow leaves
- Thinning branches
- Premature leaf drop
- Black sooty coatings
- Large numbers of ants
- Visible clusters of insects
- Branch dieback
These symptoms can provide useful information when the tree is evaluated.
Need Help Evaluating a Tree in Troy?
Sticky residue is frustrating, but the presence of honeydew does not automatically mean a tree needs to be removed.
Understanding the underlying cause is the important first step.
If your tree is also showing thinning, dead branches, structural concerns, or other signs of decline, Tree Service of Troy can help evaluate the tree and recommend an appropriate next step.
Call 855-648-7337 to request a free estimate or tree assessment.