Phenomenal Fall Migration of Monarch butterflies occurs in late September and October.
Monarchs are especially noted for their lengthy annual migration. They make massive southward migrations from August through until the first frost. Female Monarchs deposit eggs for the next generation during these migrations. The length of these journeys exceeds the normal lifespan of most Monarchs, which is less than two months for butterflies born in early summer. The last generation of the summer enters into a non-reproductive phase known as diapause and may live up to 7 months. During diapause, butterflies fly to one of many overwintering sites. The generation that overwinters generally does not reproduce until it leaves the overwintering site sometime in February and March. It is thought that the overwinter population may reach as far north as Texas and Oklahoma during the spring migration. It is the second, third and fourth generations that return to their northern locations in the United States and Canada in the spring. How the species manages to return to the same overwintering spots over a gap of several generations is still a subject of research; the flight patterns appear to be inherited, based on a combination of circadian rhythm and the position of the sun in the sky.
Monarchs can live a life of six to eight weeks in a garden having their host Asclepias plants and sufficient flowers for nectar. This is especially true if the flower garden happens to be surrounded by native forest that seems to be lacking in flowers.
