Migrants from the southern US appear in the spring, and lay eggs on a number of milkweed species, particularly along prairie river valleys. Larvae are like no other in Alberta, boldly banded with alternating black, white and yellow stripes. There are two long, black fleshy 'horns' near the front and rear. Pupae are bright blue-green with golden spots. This is undoubtedly one of the most familiar butterflies in North America, and much research has been carried out on its ecology and remarkble migration. Surprisingly, the Monarch's wintering grounds in Mexico were not discovered until 1975, largely as a result of the research efforts of Fred Urquhart (Layberry et al. 1998). Almost all of the North American Monarchs overwinter in a handful of sites in the Mexican highlands, and conservation efforts for this species are largely dependent on the welfare of these sites. For more detailed accounts of the Monarch's ecology, see Brower (1995) and references therein.