About Pachysphinx occidentalis Edwards, 1875
Pachysphinx occidentalis, commonly known as the big poplar sphinx, is a moth species belonging to the family Sphingidae. This species was first formally described by Henry Edwards in 1875. It is distributed across Canada and the United States, where it inhabits riparian areas and suburban regions. The wingspan of adult moths ranges from 130 to 150 mm. This species has two distinct color forms: the pale form has yellow-brown forewings, while the dark form has dark gray forewings. In both forms, the lines and bands on the wings are clearly defined. On the upperside of the hindwing, there is a crimson patch that can cover different amounts of the wing surface, along with two dark lines that do not form a clear triangular shape. In southern Arizona, this species has two generations per year, and adult moths are active in flight from May through September. In regions farther north, there is only one generation per year, with active adults occurring from June through August. The larvae of Pachysphinx occidentalis feed on species of cottonwood Populus and Salix.
