Was the hermit hummingbird hawkmoth described in the 20th or 21st century?

Context: Macroglossum insipida, the hermit hummingbird hawkmoth, is a moth of the family Sphingidae. It was described by Arthur Gardiner Butler in 1875.

Answer: Neither.  It was first described by Arthur Gardiner Butler in 1875, which is in the 19th century.