Brown, crusty bumps; thick, white, waxy bumps; or clusters of somewhat flattened yellow or whitish scaly bumps cover the fronds. The bumps can be scraped or picked off. Fronds may turn yellow, and leaflets may drop. In some cases, a shiny, sticky substance coats the fronds. Scales are sometimes mistaken for reproductive spores produced by the fern.
Apply an insecticide labeled for scales. Discard severely infested plants.