As shipments of tropical foliage and succulent plants are brought into greenhouses, they should be inspected for mealybugs. Mealybugs can be introduced into the greenhouse through infested tropical foliage and succulent plants. Make sure to isolate new plants in a separate area away from the main greenhouse, so they can be inspected first.
Mealybugs feed on a wide range of host plants. They cause damageby extracting plant fluids using their piercing-sucking mouth parts and injecting toxic saliva into plant tissue. This causes stunted growth, yellowing of leaves and distortion. They also excrete sticky honeydew that serves as a growing medium for black sooty mold fungi. Mealybugs can be an ongoing challenge for the grower. in greenhouses where plants are carried over from season to season.
Mealybugs are small oval-shaped insects with distinctive white, waxy filaments protruding from their bodies. Adult females are covered with white powdery, waxy secretions. Males are small short-lived winged insects that that do not feed. Mealybugs seldom move except for the first instar or crawler stage. They can be spread in the greenhouse by workers as they handle plants. Educate workers on the importance of sanitation practices in the greenhouse.
Because only adult male mealybugs fly, yellow sticky cards are not effective for scouting. Use a hand lens or magnifying glass to scout for mealybugs. Closely examine the growing tips and areas where the leaves attach to the stems. If mealybugs are found, treat plants with a labeled insecticide before introducing them into the greenhouse. Thorough coverage is important and multiple applications may be required. Read and follow label directions.
For more information on insecticides labeled for control of mealybugs on greenhouse crops, see the latest edition of the New York and New England Management Guidelines for Greenhouse Floriculture and Herbaceous Ornamentals.
- Geoffrey Njue, Extension Specialist, UMass Extension Greenhouse Crops and Floriculture Program
