Key Features
- Wax covered insects
- Sticky excrrement
- Sooty mold
Symptoms
Mealybugs are small, white insects that are closely related to scale insects. The bodies of mealybugs are covered in a waxy or cotton-like secretion. On flowers, look carefully on leaf undersides and at stem and leaf junctions for mealybugs. On ornamental grasses, look for a purplish discoloration on the leaf sheath. Peel it back and you may find a mealybug.
Biology
There are many species of mealybugs and their life cycles vary. Females lay eggs in a cottony sac and produce hundreds of eggs in their lifetime. Mobile crawlers hatch out and locate a suitable feeding site where they typically remain anchored. Most mealybugs attacking garden plants arrive on cuttings. On flowering plants, like Coleus, these species (probably citrus mealybug and long-tailed mealybug) are not hardy and will not survive the winter. On ornamental grasses, the mealybugs (Miscanthus mealybugs) can survive the winter. All stages damage plants (excluding males whose sole purpose is reproduction).
Management Recommendations
Inspect plants when purchasing them for the white, cottony tufts of mealybugs. Do not purchase those with mealybugs. Consider destroying and removing heavily infested plants in the garden. Applications of systemic pesticides (imidacloprid) are recommended for ornamental grasses because they do not flower. Other pesticides should be used on flowering plants to avoid season-long injury to bees.
Effective Pesticides
Active Ingredients include: Azadirachtin, Bifenthrin, Horticultural oil (Paraffinic or superior oil) , Imidacloprid, Insecticidal soap (Potassium salt of fatty acid), Permethrin
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