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Photo Credit: ©2005 Buglady Consulting

Longtail mealybug are easy to identify from their threadlike tails.

What do mealybugs look like?

Commonly found on houseplants, these small insects are 1-4 millimeters long. The females are covered with a white, cottony or mealy wax secretion and look like tiny cotton balls on plants, taking away a plant’s aesthetic value. They’ve got an oval body outline, and functional legs allow them to be mobile in their immature stage. Some mealybugs are more ornate than others, having filaments around the edge of their bodies or even “tails.” Immature males and females look similar, but they’re very different as adults: The adult male looks like a gnat with one pair of wings. (Only the adult males fly.) Female crawlers go though four developmental stages until they reach maturity. The male goes through five.

Adult female mealybugs can lay up to 600 eggs, usually found in a cottonylike sac beneath her body. (One exception is the longtail mealybug, which gives live birth to crawlers.) On average, within six to 14 days, the eggs start to hatch, and immature scale crawlers emerge. This stage varies with plant species and indoor temperature. When it does occur, it’s the time when dispersal to new plant parts or new plant hosts occurs. So in other words: This is when you want to target treatment!

What kind of damage do mealybugs do?

Once the crawler selects a feeding site, it inserts its mouthpart (called a stylet) and begins feeding on plant sap. While eating, a sticky waste substance is excreted by the insect (commonly called honeydew). This liquid adheres to leaves and provides a medium for sooty mold to colonize and grow. Sooty mold is black and eventually covers leaves and stems. This mold inhibits infected portions of the plant from photosynthesizing and causes aesthetic damage.

In addition to the sooty mold, plant damage is caused by the mealybugs sucking plant sap and the pests’ toxic saliva, both resulting in distorted plant growth and premature leaf drop. Plant leaves also develop yellow chlorotic spots.