and males typically mate more than once. Females that mate several times lay more eggs. Mating for the overwintering populations occurs in the spring, prior to dispersion. Mating is less dependent on pheromones than in other species in its genus. Male search and capture strategies may influence copulatory success, and human-induced changes to the habitat can influence monarch mating activity at overwintering sites. Distribution and habitat The range of the western and eastern populations of D. p. plexippus expands and contracts depending upon the season. The range differs between breeding areas, migration routes, and winter roosts. However, no genetic differences between the western and eastern monarch populations exist; reproductive isolation has not led to subspeciation of these populations, as it has elsewhere within the species' range. In the Americas, the monarch ranges from southern Canada through northern South America. It is also found in Bermuda, Cook Islands, Hawaii, Cuba, and other Caribbean islands the Solomons, New Caledonia, New Zealand, Papua New Guinea, Australia, the Azores, the Canary Islands, Madeira, continental Portugal, Gibraltar, the Philippines, and Morocco. It appears in the UK in some years as an accidental migrant. Overwintering populations of D. p. plexippus are found in Mexico, California, along the Gulf Coast of the United States, year-round in Florida, and in Arizona where the habitat has the specific conditions necessary for their survival. On the East Coast of the United States, they have overwintered as far north as Lago Mar, Virginia Beach, Virginia. Their wintering habitat typically provides access to streams, plenty of sunlight (enabling body temperatures that allow flight), and appropriate roosting vegetation, and is relatively free of predators. Overwintering, roosting butterflies have been seen on basswoods, elms, sumacs, locusts, oaks, osage-oranges, mulberries, pecans, willows, cottonwoods, and mesquites. While breeding, monarch habitats can be found in agricultural fields, pasture land, prairie remnants, urban and suburban residential areas, gardens, trees, and roadsides – anywhere where there is access to larval host plants. Larval host plants The host plants used by the monarch caterpillar include: Asclepias angustifolia – Arizona milkweed Asclepias albicans – whitestem milkweed Asclepias asperula – antelope horns milkweed Asclepias californica – California milkweed Asclepias cordifolia – heartleaf milkweed Asclepias curassavica Asclepias eriocarpa – woolly pod milkweed Asclepias erosa – desert milkweed Asclepias exaltata – poke milkweed Asclepias fascicularis – Mexican whorled milkweed Asclepias humistrata – sandhill/pinewoods milkweed Asclepias incarnata – swamp milkweed Asclepias linaria – pineneedle milkweed