The first stage after hatching is the only nymphal stage with legs, so the insects are called crawlers. Crawlers may stay under the maternal armor several hours until outside conditions, especially temperature and humidity, are good. After they leave the cover, they wander for a period ranging from minutes to days, but usually a few hours. At the end of the wandering period they flatten against the leaf or stem and begin to secrete their armor (Beardsley and Gonzalez, 1975).
Insecticide mode of action and formulation are important because the armor covers and protects all stages but the crawler and the adult male. Contact insecticides target the crawlers stage; systemics target adult females and nymphs, as well as male nymphs. Since scales have natural enemies, care must be taken to conserve these. Populations of other pests, such as white flies and other scales, may rise if their natural enemies are affected by chemical control. Spraying should be determined by presence of scales in the field rather than by the calendar. Scales are best detected by regularly inspecting all areas of the fields for scales. When detected, directing spray at hot spots rather than uninfested areas helps conserve natural enemies and also delay pesticide resistance.
In the packing house, insecticidal soaps can be used in the cleaning water to kill crawlers while scrubbing off adults. Dipping without scrubbing in a soap-pyrethroid solution for five minutes is only 70% effective against adults and nymphs (Hansen et al. 1992). Even though scales are killed, it takes several days for the body to dry, so removal of the armor is required to assure inspectors that the plant material is insect free.