Butterflies have a short life span. But there is no single species that lives for just a day--the average life span of butterflies is about a month. One of the most short-lived butterflies is the swallowtail butterfly. It lives from six to 14 days. Also, no butterfly can live for more than one year. The mourning cloak butterfly that hatches in early summer may live almost a year. Monarch butterflies may live up to six months.