DNA barcoding studies of the Arthropoda. Total number and percentage values of articles published with “barcod*” and insect*” (green), “crusta*” (blue), “chelicer*” (orange), or “myriapod*” (violet) as keywords in their topic and listed in the Web of Science (period covered: 2003-2014; n = 1,382). For crustaceans, the total number of articles is split into: 1) the number of articles removed from our analysis (duplications and false positives) (pie sector in light blue) and 2) the core number of articles used in this review (pie sector in dark blue). Arthropod illustrations were modified from Gruner (1993) and Dathe (2003).