RESUMO
Abstract The integration of field work with DNA barcoding is useful to disentangle lepidopteran interactions in nature. Adults of the little-known geometrid moth Cosmophyga cortesi Vargas, 2008 (Lepidoptera: Geometridae) were reared from folivorous larvae collected on the native tree Schinus areira L. (Anacardiaceae) at about 260 and 1500 m elevation in the transverse valleys of the Atacama Desert of northern Chile. Similarity of two DNA barcodes of C. cortesi was 99.7 and 100% with one sequence of an unidentified geometrid larva previously collected in a cell of the potter wasp Hypodynerus andeus (Packard, 1869) (Hymenoptera: Vespidae). This finding represents the first host plant record for C. cortesi, expands its previously documented altitudinal range by more than 1200 m and confirms that its larvae are captured by females of a potter wasp.