Monarch Butterfly (Danaus plexippus) 'Domestic'. This amazing butterfly is unique in North America as the only butterfly that migrates southward in the winter. In late August and early September, swarms of Monarchs gather to start the 4500 km journey to their over wintering grounds in the Sierra Amadeus mountains of Mexico. Taking advantage of air currents, these fragile creatures complete the journey in about six weeks. Over wintering monarchs are not active; they spend the winter roosting in clusters on Oyamel fir trees. In the spring, the butterflies start the journey north, mating along the way. Once they reach the southern limit of milkweed, they lay their eggs and die. Purple Cone Flowers (Echinacea purpurea) like hot humid summers, full sun, and light shade. Coneflower is a common name that is often applied to Rudbeckias, Black Eyed Susans, Chrysanthemums, and Shasta Daises. Summer. Ludlow, MA. USA. Wild