On many ornamental plants, scale insects are the most serious pests, and most ornamentals are susceptible to one or more species of scales.
Scales cause damage by sucking the juices from the plants.
Heavily infested plants appear unhealthy and produce little new growth. Scales feeding on the undersides of leaves may cause yellow spots to appear on the top sides, and these spots progressively become larger as the scales continue to feed. If the scales are not controlled, leaves will drop prematurely, sometimes killing portions of twigs and branches. Scales also feed on trunks and stems of plants. Female scales never possess wings and are disseminated primarily by infested plant stock.