Abstract Leichosila gen. n. is described based on two new species, Leichosila talamanca sp. n. and L. wagneri sp. n., from montane rain forests of Costa Rica. Leichosila is allied to the North American Hyphantria Harris generic group (subtribe Spilosomina) which is largely temperate-subtropical in distribution, suggesting that Leichosila is derived from North American faunal elements rather than Andean/South American.