Abstract
The Canterbury Museum mayfly collection of more than 11,000 tubes of specimens is described, with background including the history of Christchurch and the Canterbury Museum. Contributors to the collection, and the history of New Zealand mayfly taxonomy are briefly discussed. The collection is examined to determine whether collecting patterns over nearly one hundred years can shed light on changes in abundance of individual species. Three species are identified as giving cause for concern that they have become endangered: Ichthybotus bicolor, Oniscigaster wakefieldi, and Deleatidium (Penniketellum) insolitum.