Data from the experimental investigation of the vulnerability of early life stages of the invasive fern Lygodium microphyllum to the biological control agent Floracarus perrepae. Five initial development stages were examined: gametophyte, sporophyte, true leaf, rachis node, and mature plants. The objectives of the research were to determine what earlier life stages of L. microphyllum are susceptible to attack by F. perrepae, if damage from F. perrepae increase mortality in earlier life stages, can F. perrepae damage alter above ground and/or below ground biomass in earlier life stages, and can F. perrepae reduce the number of rachis and the number of fiddleheads in the earlier life stages. Twice a week, plant measurements were taken, measurements included longest rachis length, number of rachises, and number of fiddleheads. Upon completion of the experiment, we harvested the above and below ground biomass.Partially funded by the USDA through the Comprehensive Everglades Restoration Plan (CERP) (USDA agreement 58-6032-1-001) and through the Southwest Florida Water Management District (USDA agreement 58-6032-3-003).