Scale Insect
Coccidae / Diaspididae families
moderate risk
insect
Overview
Tiny immobile insects that attach to plant stems and leaves, sucking sap beneath a protective waxy covering. Major pests of ornamentals and fruit trees.
Adults sedentary, covered by waxy shell. Soft scales 3-5mm, oval, brown. Armored scales smaller, flat, various colors. Look like bumps or encrustations on bark.
Prevention Strategies
- •Inspect new plants carefully before purchase
- •Encourage parasitic wasps by avoiding broad-spectrum insecticides
- •Horticultural oil dormant sprays on susceptible plants annually
Control Methods
- •Dormant oil spray in late winter before crawlers emerge
- •Summer oil spray when crawlers active
- •Systemic insecticides (imidacloprid) for severe cases
- •Rub off with soft brush and rubbing alcohol for houseplants
- •Encourage parasitic wasps
Interesting Facts
- •Over 8,000 species of scale insects worldwide
- •Lac scale produces shellac - a coating still used commercially
- •Cochineal scale produces carmine red dye used in food coloring
- •Most scale insects are fertilized without males - parthenogenetic reproduction