Celastrina echo, known generally as the echo azure or western azure, is a species of blue in the butterfly family Lycaenidae. Celastrina echo have been observed in mostly western regions of the United States, including California, Oregon, Arizona, New Mexico, and Montana.

The taxonomic division of Celastrina butterflies has been a very complicated issue. Some scientists like Layberry et al. once recognized C. echo as a subspecies of C.ladon (Cramer, 1780) in western Canada. In 2001, Guppy and Shepard nominated C. echo to the species level. Currently, many scientists agree that C.echo is a distinguished species.

The MONA or Hodges number for Celastrina echo is 4363.2.

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