Perhaps the best known butterfly in North America is the Monarch Butterfly (Danaus plexippus). South Florida is very lucky this time of year, and not just for our mild climate. While most of the United States is in the middle of a frigid winter, with its Monarch Butterfly population safely hibernating in the Oyamel Fir trees of Central Mexico and Eucalyptus trees in Southern California, our population is flying about and reproducing. You see, since we have food and warmth for them year round, there is no need for our population to migrate to Mexico.
The Monarch Butterfly feeds on nectar of almost every flower, but it will only lay its eggs on plants in the Milkweed Family (Asclepiadaceae), and in our area, the Mexican Milkweed (Asclepias curassivica) is by far preferred over any other Milkweed relative. Once the eggs are laid, they hatch into caterpillars in 10 days. A chemical compound in the milkweed plant makes the caterpillar, and later the adult butterfly, very distasteful to potential predators such as birds and lizards. The caterpillars continue to feed for 2 weeks. Then the mature caterpillar leaves its host milkweed plant and encases itself in a chrysalis on a nearby shrub or sometimes a pot, or even under a windowsill. After 10 days, a beautiful Monarch Butterfly will emerge feeding on nectar for 2-6 weeks, before looking for a mate to start the process all over again. Male Monarchs have a black spot on each of their hind wings over a vein. The female is identical to the male in every aspect, except for these 2 black spots.
Now the only difference between the population in S.FL. and the rest of North America, is that in September and early October, the butterflies that emerge from their chrysalis migrate approximately 2,500 miles (depending on their location) to Central Mexico where they hibernate in Oyamel Fir Trees for the winter. They can fly 50-100 miles per day, so depending on where they begin their migration, it can take 30-60 days to complete the journey. These late season butterflies live for 6-8 months, whereas butterflies metamorphosing during the rest of the year only live for 2-6 weeks, similar to the population in S.FL. Then, starting in March, they start migrating north breeding and finding milkweed plants to lay their eggs on along the way.