Thanks for your question.
I'll begin by breaking down the components of Eisenia fetida. Eisenia
refers to the genus and fetida the species.
Classification of Earthworms
According to Webster's Unabridged dictionary, the word derives from
Gustav A. Eisen [there are assorted variations on this name], an
American zoologist and archeologist. Eisenia itself refers to "a
widely distributed genus of small earthworms."
Webster's Unabridged Online
Eisen was born in Sweden in 1847 and came to the United States in
1873. He died in 1940.
August Gustav Eisen
Eisen apparently was a man with many interests, including Mayan
culture, beads, textiles, and zoology.
Maya Textiles of Guatemala: the Gustavus A. Eisen Collection
Bead Researchers Hall of Fame
In keeping with these varied interests, he authored a number of books,
including "On California Eudrilidae," "Researches in American
Oligochaeta," "Pacific coast Oligocheta" (about worms) as well as
"Portraits of Washington," "Raisin Industry" and "Great Chalice of
Library of Congress
eisenia fetida taxonomy
I also checked the Library of Congress catalog (basic search: eisen,
g) to make sure that Gustavus and Gustav Eisen were the same
I hope this answers your question. If you need additional information
or if the links don't work, please ask for additional clarification
before rating my answer and I'll do my best to assist you.