Problem: Scale Insects (Ferns)
Several different types of scale insects attack ferns. The young, called crawlers, are small (about 1/10 inch) and soft bodied and move about on the plant and onto other plants. After moving about for a short time, they insert their mouthparts into the plant, feeding on the sap. The legs disappear, and the scales remain in the same place for the rest of their lives. Some develop a soft covering, others a hard covering. Some species of scales are unable to digest all the sugar in the plant sap, and they excrete the excess in a fluid called honeydew.
Isolate infested plants as soon as scales are discovered. Remove as many scales as possible with a cloth or toothbrush dipped in soapy water. Apply an insecticidal soap or horticultural oil, following label directions. Avoid bringing scale crawlers into the house.