The light green cylindrical eggs have vertical ribs. Mature larvae are grey-brown with fine yellow and black markings and yellow branched spines (Guppy & Shepard 2001). Larvae live in silken leaf-nests on the hostplant (Layberry et al. 1998). This species is rare or absent in Alberta in most years, but in years that populations build up in the southern United States, worn and often tattered migrants appear in May to lay their eggs, having flown thousands of miles. The offspring of these migrants emerge from July onwards. Since it is rare or absent in most years in Alberta, it is thought that Painted Ladies cannot overwinter here, and re-colonize in good migrant years. It is not known if summer brood individuals attempt a southward return migration in the fall here; they may in the southwestern US (Scott 1986), but there is no evidence they do so in British Columbia (Guppy & Shepard 2001).