Mealybugs (Pseudococcidae) are soft-bodied, wingless insects that look like a white cottony mass on the leaves, stems, and flowers of plants. They can cause leaf yellowing and curling of leaves as the plant weakens from high numbers of Mealybugs.
Common removal techniques include pruning all infested plants in high amounts. Otherwise dabbing small amounts of rubbing alcohol on them with a cotton Q-tip works but is time consuming.
This infestation was on the pineapple sage in the greenhouse.