RESUMEN
We describe here for the first time the complete immature life cycles and shelter structures of two Neotropical skipper butterflies in the subtribe Moncina, Troyus phyllides (Röber, 1925) and Thoon ponka Evans 1955, along with new natural host plant records for these species at Finca Las Piedras, Madre de Dios, Peru. Four eggs and a preantepenultimate larva of T. phyllides, as well as three eggs of Thoon ponka were collected in nature and each passed through five larval instars to adulthood. Troyus phyllides fed on a herbaceous species, Lasiacis ligulata Hitchcock & Chase (Poaceae: Panicoideae: Paniceae), while T. ponka fed on two congeneric herbaceous bamboo species, Pariana lunata Nees and Pariana sp. (Poaceae: Bambusoideae: Olyreae). We present photos of all immature stages and host plants, as well as illustrations of the shelter structures and the head capsules for each of these two species.