Some groups of Monarchs migrate for over 2,000 miles during August-October, flying from Canada and the USA to overwinter in coastal southern California to the transvolcanic mountains of central Mexico; this was determined by the Canadian scientist Dr. Fred A. Urquhart in 1975. Females lay their eggs along the migratory route. This migration takes up to three generations of Monarchs to complete.
Other Monarchs stay in one area their entire lives. The life span of the adult Monarch varies, depending on the season in which it emerged from the pupa and whether or not it belongs to a migratory group of Monarchs. Adults that emerged in early summer have the shortest life spans and live for about two to five weeks. Those that emerged in late summer survive over the winter months. The migratory Monarchs, which emerge from the pupa in late summer and then migrate south, live a much longer life, about 8-9 months.