According to Flags of the World, the Ecology Flag was created by cartoonist Ron Cobb,
published on November 7, 1969, in the Los Angeles Free Press, then placed in the public domain.

The symbol is a combination of the letters "E" and "O" taken from the words "Environment" and
"Organism," respectively. The flag is patterned after the United States' flag, with thirteen alternating-green-and-whites stripes. Its canton is green with a yellow theta. Later flags used either a theta, because of its historic use as a warning symbol, or the peace symbol. Theta would later become associated with Earth Day.