In Fall 1939, as war engulfed Europe, the author of one of the most influential texts on genetics and evolution, Theodosius Dobzhansky, wrote a letter to curator of insects at the United States National Museum, Edward Albert Chapin. Dobzhansky wished to know what Chapin thought about his pursuing some taxonomic work on an old fascination of his: lady-bird beetles. This paper examines the resulting correspondence as a window into Dobzhansky’s attitude toward taxonomy, the different pressures on geneticists and taxonomists when (...) wrestling with how to name species, the relation between biological theory and taxonomic practice, and how claims regarding human races may have motivated Dobzhansky’s continued interest in the work of beetle taxonomists. In doing so, this article builds on the work of Paul Farber and others to highlight the importance of including museums, taxonomy, and the naturalist tradition within the history of twentieth-century biology. (shrink)