If you slept through science class, here's why you see so many of them during the fall.

Patricia S. York

If you anticipate the fall migration of hummingbirds and lovingly provide food and shelter for the tiny creatures as they head south, you probably keep watch for the Monarch butterflies, as well. Like the hummingbirds, Monarchs do not tolerate cold very well, so they also take an autumnal pilgrimage to warmer weather. If you missed the science lecture in grammar school, read on for some truly interesting facts about the magnificent and colorful Monarch butterfly, and how you can attract and nourish them in your garden.

The Importance of the Milkweed Plant

All butterflies change their diet as they develop. As caterpillars, they need a host plant to eat and, as butterflies, they need nectar plants on which to feed. Monarch butterflies lay their eggs only on milkweed plants, which then become the exclusive food source for the caterpillars, once they hatch. The milkweed plant is a sun-loving perennial that is easily grown in your butterfly garden. An important food source for the Monarchs, milkweed contains glycoside toxins, harmless to the Monarchs, but poisonous to its predators (as well as humans and pets). Adult Monarchs will then feed on nectar from the flowers of the milkweed plant, as well as a wide range of other flowers.

Which came first: The butterfly or the egg?

The study of butterflies is truly captivating; you simply stand in amazement when you try to fathom the complex and ancient instincts that drive a creature as small and delicate as the butterfly. Here is a quick lesson in natural science:

In early spring, the Monarch butterflies that wintered in the warm climates of Mexico begin to make the journey north to the United States. Along the way, pairs of Monarchs will mate and, as they reach the Southern states, females will look for the important milkweed plants to lay eggs. The tiny eggs hatch after approximately four days and the caterpillars begin ravenously devouring their host plant, growing exponentially over a two-week period. Once big enough, each caterpillar forms a chrysalis and goes through metamorphosis. About two weeks later, the beautiful adult Monarch butterfly emerges to continue the journey north that was left unfinished by its parents, and begins the cycle all over again.

Each year, about three to five generations will be born to continue migrating north. Here is one of the interesting parts about the nature of the butterflies: most Monarch butterflies do not live more than a few weeks. It is only the last generation that is born in late summer that will live for several months (upwards of eight months). It is these late summer Monarch butterflies that gardeners see flitting around the flowers, gathering sustenance for the long migration to Mexico, where they will spend the winter and start the cycle all over again when the weather warms the following year.

How to help

According to the National Wildlife Federation, the Monarch population has declined tremendously since the 1990’s. Factors such as climate change and diminishing habitats are making it hard for the Monarchs to sustain their life cycle. Here are ways you can help:

Include milkweed plants, the sole host plant for Monarch caterpillars, in your butterfly garden.

Provide a food source for the adult Monarchs by planting nectar plants that will bloom early, mid, and late summer.

Butterflies need a place to rest, such as flat stones and rocks scattered throughout your garden.

Provide clean, pesticide-free water for butterflies to drink. Butterflies are often seen “puddling” – drinking water and extracting minerals from damp areas of the ground. Fill a shallow pan halfway with coarse sand and moisten with water. Place it in your garden and butterflies will use it to drink and collect the minerals they need – just remember to keep adding water.