Surveys for natural enemies of Lygodium microphyllum (Cav.) R. Br. (Lygodiaceae) in Thailand resulted in the collection of Archips machlopis Meyrick (Lepidoptera: Tortricidae). Multiple generations of the tortricid were reared on L. microphyllum in a quarantine laboratory, demonstrating that the plant is a developmental host. Further host specificity testing indicated that A. machlopis is able to complete development on 12 of the 15 fern species tested, confirming that the polyphagous herbivore's diet includes Pteridophyta. These data also confirm that A. machlopis is not sufficiently host specific to be considered for biological control of L. microphyllum.