Scale Insects & Mealybugs

Updated September 24, 2026 · The Pest Guide · Editorial policy

You might spot what looks like a tiny speck of white cotton hiding in the leaf joint of your favorite houseplant, or a smooth brown bump glued tight against a citrus stem, and wonder what on earth is going on. What pulls scale insects and mealybugs into one single group is their shared craving for plant sap and the trick of covering themselves in wax. Whether that wax puffs up into a powdery dusting or hardens into a rubbery dome, it acts as a shield that makes these slow-moving bugs notoriously tough to wash away. As they feed on your greens, they process massive amounts of liquid and excrete a sticky waste called honeydew that quickly turns leaves black and glossy with mold.

Tell this bunch apart from other garden visitors by checking how they move and what mess they leave behind. Aphids have long legs and tiny tubes poking out of their rear ends, while whiteflies flutter off in a cloudy swarm the second you brush a leaf. Mealybugs and scale insects never fly away, and adult females either shuffle along very slowly or stay permanently glued in one spot. If you notice sticky droplets coating the furniture beneath your indoor ficus or ants marching up a woody stem to farm the sweet secretions, you are looking right at this group.