NEW INFORMATION: The following new information regarding C.orientalis is provided in this study: Carnusorientalis is first recorded in Taiwan, filling the gap in its East Asian distribution. This is also the first record of Carnidae from Taiwan.Otuslettia (Hodgson, 1836) (Aves, Strigidae) is reported as a new host for C.orientalis, identified on a fallen fledgling.Co-amplification of the host's COI is reported in this study using the universal PCR primer set LCO1490/HCO2198. Additionally, the amplification of a COI-like pseudogene using a newly-designed primer set is detected through abnormal translated amino acid sequences and the occurrence of a stop codon.New specific primers for the COI gene of Carnus were designed in this study. The new distribution and ecological data of C.orientalis enhance our understanding of this species. The provision of new COI primers is anticipated to contribute to future studies employing DNA barcoding in bird-parasitic flies.