Hornworm Moon "Worm Moon" is a term for the March full moon. Early references to it attribute it to Native American culture without specifying a language or nation. Dakota is sometimes claimed as the source; if this is true, it appears to be a less common term than Iśtawićayazaŋ-wi, "Sore Eyes Moon."

So named because it is when earthworms and other such things emerge from the earth, on account of the warming temperature.