Female scales begin to secrete the adult armor at the rear of the second stage armor. Males emerge from their second stage armor as tiny, gnatlike insects that crawl or fly to female scales to mate. When populations become dense, females tend to lay male eggs so that heavily infested plants become conspicuously spotted by second stage male armor. When fern scales are encountered, horticultural oils give adequate control without excessive phytotoxicity to ferns. Two thorough treatments 2 weeks apart should give good control.
Ferns are notoriously sensitive to pesticides.
Whenever treating ferns and other sensitive plants, treat at a time that the pesticide will be dry on the foliage before the plants are exposed to full sunlight. For specific chemical control recommendations, see current Cooperative Extension publications on ornamental plant pest management or consult your county Extension agent.