Black flies (Diptera: Simuliidae) are important blood sucking insects because they are the vectors of disease agents transmitted to human and other animals. Rapid and correct species identifications are necessary for all aspects of the study of black flies. DNA barcodes based on mitochondrial cytochrome c oxidase I (COI) have been effectively used for the determination of black fly species. However, the success of this method requires a large and reliable COI sequence library. In this study, 171 DNA barcoding sequences from 17 black fly species were added to NCBI GenBank database, six of these species were reported for the first time. Efficacy of DNA barcodes for species identification was examined using 1,286 sequences representing 89 nominal species of black flies in Thailand. A considerable level of success (90%) was achieved but efficiency of COI sequences for species identification was very low in the following species-groups; Simulium asakoae, S. feuerborni, S. multistriatum and S. striatum. Incomplete lineage sorting or inadequate variation of this genetic marker for differentiation of recently diverged species are the more likely explanations, and thus, more variable genetic markers are needed. Other reasons for unsuccessful DNA barcoding are imperfect taxonomy and the misidentification of sources of reference sequences. Because many new black fly species in Thailand were described recently, a reassessment of the COI sequences reported previously is necessary.

黑蝇（双翅目：拟蝇科）是重要的吸血昆虫，因为它们是传播给人类和其他动物的病原体的载体。黑蝇研究的各个方面都需要快速和正确的物种识别。基于线粒体细胞色素c 的DNA 条形码氧化酶 I (COI) 已被有效地用于测定黑蝇种类。然而，这种方法的成功需要一个庞大而可靠的 COI 序列库。本研究将17种黑蝇种的171条DNA条形码序列加入NCBI GenBank数据库，其中6种属首次报道。使用代表泰国 89 种名义黑蝇的 1,286 个序列检查了 DNA 条形码对物种识别的有效性。取得了相当大的成功 (90%)，但在以下物种组中，用于物种识别的 COI 序列的效率非常低；Simulium asakoae、S. feuerborni、S. multistriatum和S. striatum. 用于分化最近分化的物种的遗传标记的不完整谱系分类或变异不足是更有可能的解释，因此，需要更多可变的遗传标记。DNA 条码编码不成功的其他原因是分类不完善和参考序列来源的错误识别。由于最近在泰国描述了许多新的黑蝇物种，因此有必要重新评估先前报告的 COI 序列。