The armored scales secrete a wax covering, the shape of which is characteristic for any given species. Under this coat, the insects develop and feed, sucking the sap of plants with their thin tubular mouthparts. The females never leave the protection of the scale after once forming it, but the adult males, which do not feed, develop a single pair of wings, leave the scale, and seek out the females, fertilizing them after the females are under the shell. Among the important armored scale pests of citrus, other fruits, and ornamentals are the San Jose scale , the oyster scale, the purple scale, and the California and Florida red scales. Unarmored scale pests of citrus fruits include the black scale and citricola scale.
Mealybugs appear as white cottony clusters on citrus, ornamentals, and greenhouse plants.
Like other scale insects, newly hatched nymphs, called crawlers, have legs and actively seek out food. When they find a suitable spot, they settle down to feed. Control of scale insects has been largely by use of natural enemies, especially ladybird beetles and small parasitic wasps, which are natural predators of these pests. Scale insects have proved difficult to control by chemical means. Scale insects are classified in the phylum Arthropoda , class Insecta, order Homoptera, superfamily Coccoidea.