Dataset of forewing length of Japanese and Taiwanese butterfly species

Revealing how species assemblages are structured is one of the themes in community ecology and macroecology. The information of species traits as well as geographic occurrence would help analyze the pattern and process of species interactions and community assembly. Butterfly species are one of the best‐studied groups about their distribution and tons of their occurrence data exist. Also, life history traits, especially interaction with host plants are well‐described. However, the body size information is still poor although this is one of the most important characters affecting their distribution and life history traits. Here, we constructed a data set of the forewing length of butterflies by extracting the information from five Japanese and Taiwanese picture books. We measured 6,211 forewing lengths for a total of 524 species. Scientific, family and common names of the butterflies distributed in Japan were based on a Japanese picture book, and the other species distributed in Taiwan were based on Taiwanese picture books. Also, we added the information of butterfly names based on Binran database. Each record of butterflies is linked with the corresponding taxonomic names in the other two books to easily identify the species even when the names used in the three books and the Binran database are not the same. The dataset will be useful for basic and applied biological studies of butterflies because their forewing length is a proxy of their body size and dispersal ability, which could be important determinants of their physiology, distribution, ecosystem functioning and evolution.