Sticky drip from our HOA's trees is coating cars and sidewalks. What is it and what should the board do?

By OurHOA · General information · Revised October 31, 2026

Sticky drip on cars under HOA trees is honeydew from aphids, scales or whiteflies. How a board finds the insect, cleans up early, treats rarely and replants.

Part of the HOA board handbook: vendors, projects and upkeep.

The short answer

The sticky film on windshields and walks under a shade tree is almost never sap. It is honeydew, the sugary waste of aphids, soft scales, whiteflies and similar insects feeding in the canopy. Colorado State University Extension fact sheet 5.511 says honeydew can cover leaves, branches, sidewalks and anything else under an infested plant, and a grayish sooty mold then grows on it. The board's job: identify the tree and the insect, wash surfaces while the honeydew is fresh, treat a tree only when the drip is chronic over a busy spot, and stop planting honeydew trees over parking. The tree itself is usually fine. Washington State University's linden aphid sheet says the honeydew does not harm the tree, and Texas A&M AgriLife reports that aphid outbreaks on pecans often crash on their own. That gives the board time to plan. Pesticide licensing and label rules differ by state, and your governing documents decide who maintains which trees, so treat this as general guidance, not legal advice.

Find the tree and the insect

Walk the property on a dry morning, find the wettest or blackest spots and look straight up. Write down the species, location and what sits underneath: assigned spaces, the pool deck, a bench. Then turn over a few low leaves and check the twigs. The usual suspects: - Aphids. Small, soft, often green or yellow, clustered on new growth and leaf undersides. CSU shows chronic linden aphid infestations staining walls and walkways, and PlantTalk Colorado says ash leaf curl aphid on green ash can drip enough to coat cars, patio furniture and sidewalks. - Pecan aphids in Texas. Texas A&M says blackmargined aphids typically build from June to August and often decline after about 3 weeks, while yellow pecan aphids increase later in the season. - Soft scales. Bumps on twigs and bark that do not move. The University of Kentucky's tuliptree pest guide says tuliptree scale produces large amounts of honeydew. Our guide on treating crape myrtle bark scale covers the white, felted scale behind the black trunks on crape myrtles across the South. - Whiteflies in Florida. UF/IFAS publication EENY-578 says rugose spiraling whitefly honeydew and wax fall onto cars, patios and furniture, and females sometimes lay their spiral egg patterns right on cars, windows and walls. CSU notes that ants, yellowjackets, flies and bees gather on honeydew, so a line of ants up a trunk is a good clue. If nobody can name the insect, take a bagged twig to the county Extension office before paying for any treatment.

Clean up before the mold sets

When you clean matters more than what you clean with. PlantTalk Colorado's advice is to clean the area under an infestation before sooty mold has a chance to develop. Fresh honeydew rinses off with water. EENY-578 warns that dried sooty mold does not wash off easily and may need pressure washing or professional cleaning. A routine for the weeks the drip is active: - Common walks, pool decks and furniture. Put washing in the landscape or janitorial scope, weekly during heavy drip. - Pools under infested trees. EENY-578 says honeydew, wax and insects that land in pools can change water chemistry and clog filters. Tell the pool service so it checks filters more often. - Cars. Owners clean their own, so warn them early. Kentucky's guide says honeydew can spot the windows and finish of cars parked under infested trees, so the message is to rinse within days, not weeks. WSU suggests washing aphids off with a strong stream of water. That works on shrubs and small trees, not a 40-foot oak.

Decide whether to treat the tree at all

Most summers, the right call is not to treat: - Many outbreaks end on their own. Texas A&M says yellow pecan aphid infestations often crash because of natural enemies, rain and wind. - Spraying can make it worse. The same Texas A&M guide warns that insecticides can destroy those natural enemies and let aphids rebound to higher numbers. - Big trees are hard to treat from the outside. A UF/IFAS Okaloosa County Extension page calls spraying a large tree impractical and uneconomical, and WSU tells homeowners not to spray foliage on trees over 10 feet tall. Treat when the same healthy tree drips every year over a busy spot and the insect is known. Roughly in this order: 1. Dormant horticultural oil before bud break, for aphids that overwinter as eggs. CSU names lindens among them. It does nothing for leafcurling ash aphids, which do not overwinter that way. 2. Insecticidal soap on shrubs and small trees. CSU notes it lasts minutes to hours and only kills insects it touches. 3. A soil-applied systemic such as imidacloprid for chronic trees. CSU says root uptake usually takes a couple of weeks in warm, moist soil and control can last several weeks to a couple of months. Texas A&M lists a soil drench around the dripline for pecans. CSU also says soil systemics should not go on plants that are flowering or about to flower, because the chemical can show up in pollen and nectar. The label sets the rate and timing.

Hire licensed help and write it into the scope

Treating common-area trees for pay is regulated work. In Texas, Occupations Code 1951.003(a)(1)(B) puts identifying and controlling pests of trees and shrubs in a park or next to a residence, business or street inside the business of structural pest control, and 1951.301(b) requires a structural pest control business license for it. Ask for the Texas Department of Agriculture license number. In Florida, a landscape worker holding only the limited certification in Fla. Stat. 482.156(1) may use products with no signal word or the word "caution," with handheld or backpack equipment and never power equipment. Drenching a mature shade tree belongs with a licensed pest control company. Elsewhere, ask which state license covers the work and check it with the agriculture department. Lines to add to the landscape or tree care contract: - "Contractor will note honeydew drip and sooty mold at [locations] on each visit and identify the insect involved." - "Walks, pool deck and furniture at [locations] will be washed every 7 days from [month] to [month], or until the drip stops." - "No insecticide will be applied to a common-area tree without written board approval naming the tree, product, method and date. No soil systemic will be applied to a tree in bloom or about to bloom."

What to tell owners

One notice heads off most complaints: "Many owners have noticed a sticky film on cars and walks near [location]. It is honeydew, the waste of small insects feeding in the trees, not sap, and it does not mean the trees are dying. It rinses off while fresh but is much harder to remove once black mold grows on it, so wash your car within a few days. The association is washing common walks and furniture weekly and has asked [vendor] to identify the insect. Questions go to [board email]." Some owners will ask the association to pay for detailing or to remove the tree. Promise neither on the spot. Our guide on handling a vehicle damage claim against the HOA covers the incident form and insurer notice, and whether the association owes anything depends on your documents and state law. For removal requests, get an arborist's view of the tree's health first. One bad honeydew year may not repeat.

Plant for the parking lot you have

When a tree over parking dies or comes out, do not put the same species back. WSU says lindens along streets and in parking lots are commonly infested with linden aphids, and the Okaloosa County page notes pecans commonly leave sooty mold on plants beneath them. Ask the county Extension office or a certified arborist for local trees with fewer sucking-insect problems, and add one line to the landscape plan: no heavy honeydew trees over parking, pool decks or seating. Until then, move benches and picnic tables out from under the worst trees.

A sample season and a motion

A Texas community with pecans over guest parking might run the year like this: - May: map drip spots and have the vendor identify the insects. - June: start weekly washing and send the owner notice. - July and August: keep washing and watch. Many blackmargined outbreaks fade in about 3 weeks. - September: if the same tree dripped heavily for a second year, get a licensed bid for next season or list it for replacement. - Winter: approve the planting rule. In Colorado, schedule dormant oil for lindens. Sample motion: "Move that the association add weekly washing of [locations] from [month] to [month] to the landscape scope at a cost not to exceed $[amount], approve [licensed vendor]'s bid not to exceed $[amount] for a soil-applied treatment of trees [IDs] outside bloom, and adopt a rule that no tree known for heavy honeydew will be planted over parking or common seating."

Mistakes boards make

- Calling it sap and assuming the tree is sick. - Spraying the whole canopy after the first complaint, which kills the predators that end most outbreaks. - Letting the drip dry. Weekly rinsing in June beats pressure washing black walks in October. - Buying fungicide for the black film. The mold lives on the honeydew, so stop the honeydew and wash. - Drenching a tree that is about to bloom. - Removing a healthy shade tree after one bad summer, then planting another honeydew tree in its place.

Sources

These guides are general education for HOA boards and residents, not legal, tax, or financial advice. Rules vary by state and by your community's governing documents - check with a professional for your situation.

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