Answer: Orchids become infested with mealybugs in some combination of three methods: purchase of an infested plant, movement from infested to un-infested plants that are in contact with each other, and windblown colonization. Mealybugs are active and will crawl from one plant to another, pot to pot, and across benches. Mealybugs will leave plants and hide under rims of pots and trays, in bench crevices, and even drop from overhead plants. Spread of crawlers can occur both indoors and outdoors by floating on breezes or air currents produced by circulating and heater fans. The occurrence of infestation hotspots may be due to crawlers settling on plants where the air currents are the weakest. Mealybugs wander in search of feeding places and will leave plants, so be sure to check for them in cracks and in joints on benches, under lips of pots and trays, and other hiding places.
Mealybugs are extremely difficult to control and once the population surges, you're in for a real challenge. Safer's Insecticidal Soap is quite effective because it has fatty acids which coat the pests and effectively suffocate them. But, repeat applications may be necessary because eggs will continue to hatch if they're on untreated parts of the plant. Another method of control is to dab each mealybug with a Q-Tip dipped in rubbing alcohol. Best wishes with your orchids.
Q&A Library Searching Tips