About Monarch Butterflies and Milkweed & Milkweed Phenology
Monarch butterflies are known for their incredible migratory journey. Each year, they travel thousands of miles from their breeding grounds in the northern United States and Canada to overwintering sites in Mexico. This migration occurs in the fall and is driven by environmental cues, such as day length and temperature. Monarchs enter a state called "reproductive diapause" during this migration, which means they delay reproduction until they reach their destination. In the spring, the butterflies start heading north, beginning a multi-generational migration back to northern breeding grounds.
Reporting sightings to Journey North
Journey North collects sightings of monarch eggs, larvae, and adults, with an emphasis in the spring on volunteers' first sightings in each category.
In the fall, Journey North continues to accept sightings in all of these categories, while adding an emphasis on collecting reports of fall roosts. In the fall, monarchs travel alone during the day. At night, they come together to form roosts, gathering in trees. These gatherings, whether they're of 10 monarchs or 1,000, are a key indicator of migrating monarchs.
