Question: What is that white stuff on my orchids?
Mealybugs are serious pests of orchids and next to scale insects are probably the most difficult to control pests of orchids. Most definitely, they need to be dealt with immediately upon discovery.
The damage done to plants by mealybugs is considerable, causing a loss of vigor and a weakening and loss of leaves, buds, and flowers through their feeding. In addition, mealybugs create copious amounts of honeydew which make plant parts sticky and attracts ants. (Want to get rid of ants? Check out the other posts in my How to Care for Orchids – Pests and Disease series.)
Probably the most popular home remedy against mealybugs is to swab and daub plants with a cotton-tipped swab or ball of cotton dipped in isopropyl (rubbing) alcohol. On hard-leaved plants, gentle rubbing with the fingers, a cotton ball, cotton-tipped swab, or a soft infants toothbrush is effective. Remove all mealybugs, large and small. Afterwards, you will still need to repeat the alcohol treatment to remove the tiny yellowish spots which are the recently hatched crawlers. Pay particular attention to the folds, crotches, branch bases, midrib areas, and roots. Spraying the alcohol with a misting bottle or small pump sprayer is effective, but dribbling alcohol into tight areas is necessary as eggs are often well hidden, hence the need for thoroughness and repititon.
Many home growers will mix with alcohol a small amount of mild liquid dish detergent, and sometimes mineral oil, neem concentrate, or horticultural oil. Vegetable oils will work, too, but in sunlight they can turn rancid quickly, and become smelly and lose effectiveness. One recipe for a 1.5 liter spray bottle is to mix a 50:50 solution of isopropyl and water, with a few drops to about a teaspoon of liquid soap to act as a spreader, and a teaspoon of one of the oils.
ps. Don’t forget to check out Ryan’s Free Growing Orchids Tips. He offers incredible advice all about Orchid Pests & Diseases!
Warmest wishes from sunny Florida,
The Orchid Care Lady
+ Courtesy of South Dakota State University