Maple Tree Dripping Sticky Sap? It's Likely Slime Flux, Not Aphids

Identifying the Real Culprit Behind the Mess

Brown, frothy, sweet-smelling puddles under your maple—without visible aphids—point to slime flux (wetwood), a bacterial heartwood infection. Internal fermentation generates gas pressure (up to 60 psi), forcing nutrient-rich sap through bark wounds. The ooze attracts flies, bees, and wasps.

Slime Flux vs. Aphid Honeydew

Management: Support, Don't "Cure"

• No effective treatment eliminates internal bacteria—injection risks spreading infection.
• Surface disinfection: 10% bleach solution (1:9 bleach:water) on flux areas reduces insect attraction and bark damage.
• Cultural care: Water during drought, avoid fertilization unless soil test indicates need, prevent wounding.
• Accept coexistence—many trees live decades with slime flux.

When to Worry

If large limbs begin failing with hollow centers, or if decay spreads to structural roots, consult an arborist for hazard evaluation. Otherwise, manage the mess and maintain tree vigor.