MonitorLeavesInsects

Why is my tree dripping sticky sap on everything?

A shiny, tacky film on leaves, and on everything parked or set under the tree — sometimes followed by a black sooty coating on the same surfaces.

Watch it, correct the care behind it, and check again next season. Nothing here threatens people or property in its current state.

This is a nuisance far more than a health problem. Honeydew is a sign of insects feeding on sap, and established shade trees tolerate that feeding for years. The reason to pay attention is that heavy scale on a tree already short of water can tip it into visible decline, and scale is much easier to manage before it is established.

What this looks like

The first sign is usually not the tree at all. It is a windshield that will not wipe clean, a patio table that stays tacky, or a driveway that feels sticky underfoot in July. On the tree, the upper leaf surfaces glisten in the light. Weeks later a black film develops on the stickiest surfaces — a harmless mold growing on the sugar, not an infection of the leaf.

Leaves that shine unnaturally in low sun and feel tacky between your fingers
Clear droplets falling steadily enough to spot dark pavement below
Black film on upper leaf surfaces, car paint, and furniture that wipes off wet
Wasps, ants, and flies working the canopy in numbers, harvesting the sugar

What causes it in Kansas

Roughly in order of how often each turns out to be the answer here. The line under each one is what separates it from the others — open a cause for the detail.

1Aphids
How to tell: Clusters of small insects on the underside of leaves and at new shoots, with white cast skins accumulating below them.
Soft-bodied insects that feed in colonies on shoot tips and leaf undersides, passing sap through and excreting the excess sugar. Silver maple, hackberry, elm, and honeylocust are the reliable Kansas producers. Populations usually crash on their own by mid-summer once lady beetles, lacewings, and parasitic wasps find them.
2Soft scale
How to tell: Bumps along twigs that scrape off with a thumbnail and are wet underneath, with no visible legs or movement.
Immobile insects that look like small brown or waxy bumps on twigs and leaf undersides. Lecanium scale on oak, elm, and maple, and magnolia scale, are the heavy honeydew producers here. Unlike aphids, they persist for years and can genuinely weaken a stressed tree.
3Sooty mold
How to tell: Black coating that rubs off and leaves green tissue underneath, always found where something sticky came first.
A group of fungi that colonize honeydew. They live on the sugar, not on the leaf, and disappear as soon as the insects producing the sugar are gone.
4Spider mites
How to tell: No stickiness anywhere. Tap a branch over white paper and watch for moving specks.
Included here because people expect them and they behave differently: mites cause fine pale stippling and a bronzed, dusty look, but they produce no honeydew at all. Hot, dry Kansas summers favor them.
5Normal spring bleeding
How to tell: Clear liquid coming from a specific wound or cut end, in February through April, with nothing on the foliage.
Sap running from a pruning cut or wound on maple, birch, elm, or walnut in late winter and early spring is water moving under root pressure, not an insect problem.

Most often on:Silver Maple Common Hackberry Honey Locust (thornless)American Elm

What to do, and what to avoid

Safe to check yourself

All from the ground — no ladder, no saw.

Turn over a dozen leaves from the sticky part of the canopy and look for insects, cast skins, or bumps
Rub the black film with a wet cloth to confirm it lifts off and the leaf is green underneath
Tap a branch over a sheet of white paper to separate a mite problem from an aphid problem
Check whether beneficial insects are already at work before deciding to intervene

What not to do

The responses that make this one worse or permanent.

Do not spray insecticidal soap or oil in 95-degree heat, which burns foliage
Do not apply a broad-spectrum insecticide, which kills the lady beetles and parasitic wasps that were about to solve this for free
Do not use a soil-applied systemic on a tree that is flowering or about to flower, because the residue reaches pollinators
Do not pressure-wash bark to clean off sooty mold

When to contact an arborist

Scale is heavy on a tree already showing thin growth or dieback, the honeydew problem returns for a third season, or the tree is too large to inspect from the ground. Scale control depends on hitting a narrow window when the mobile crawler stage is active, and that window is identified by monitoring rather than by the calendar.

Whatever this narrows it down to, the assessment that decides what happens next has to happen at the tree. Why that is

Common questions

Will the sticky residue hurt my car's paint?

Honeydew and the sooty mold that follows are not corrosive, but they bond hard in sun and get abrasive to remove. Wash it off sooner rather than later, or park somewhere else through July and August.

Should I hose the aphids off?

A strong jet of water knocks colonies off small trees and is a reasonable first response, since dislodged aphids largely do not make it back up. On a mature shade tree you cannot reach enough of the canopy for it to matter, and patience works better.

Does sooty mold need to be treated?

No. Remove the honeydew source and the mold weathers off over a season. Fungicides do nothing useful here, because the fungus is not attacking the plant.

Kansas Tree Guide is an independent educational resource. Nothing on this site replaces an on-site assessment by a qualified arborist or tree-care professional. Last reviewed August 2026.

Often seen alongside this

A second symptom narrows the cause faster than more detail about the first.

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