'Northern' Oak Hairstreak (Satyrium favonius ontario) (Lepidoptera: Lycaenidae): Status Survey in Massachusetts, False Rarity, and Its Use of Non-nectar Sugar Resources

摘要

Satyrium favonius ontario is considered to be one of the rarest eastern butterflies. We conducted a status survey and studied the ecology of this hairstreak at Great Blue Hills Reservation in Canton, MA-New England's most reliable colony. Burlap banding to sample larvae proved to be a more productive censusing technique than traditional time-intensive and weather-dependent adult searches. Our preliminary data suggest that Leucobalanus (white and post) oaks serve as the primary hosts for the butterfly in the Northeast. We supply a larval key and diagnoses that will allow accurate identification of four synchronic and sympatric thecline lycaenids associated with Quercus (oaks) in New England. We document adults of four congeneric Satyrium hairstreaks (S. calanus, S. caryaevorus, S. edwardsii, and S. liparops) feeding at pip galls on Quercus ilicifolia made by the cynipid gall wasp Callirhytis balanacea. We present arguments that adults of S. f. ontario are canopy-dwelling animals that feed on non-nectar resources (such as galls and Hemiptera honeydew) and that floral nectars, while used commonly by the adults, may be unnecessary as a source of nutrients when other non-nectar resources are available. We conclude with a discussion of how the use of such resources, combined with canopy-dwelling behavior, may yield an impression of great rarity, and that conservation agencies seeking legal protection for S. f. ontario may want to do so guardedly.