Published online by Cambridge University Press: 31 May 2012
On 5 September 1982, the third coauthor collected a single male of an unfamiliar geometrid moth in Vancouver, British Columbia. He sent it to the first coauthor, who recognized it as a species of Ennomos related to our native maple spanworm moth, E. magnaria Guenée. The second coauthor identified it as Ennomos alniaria (L.), a European species known in Britain as the canary-shouldered thorn.