By Vanessa Gayton
Editor’s note: Originally released in November 2013, this article has undergone updates and revisions as of January 2024.
As seasons change, millions of Monarch butterflies migrate to the same wintering grounds along the northern coasts of California and Mexico. This remarkable journey spans an impressive 3,000 miles and involves three to four generations of Monarchs. They rely on cues from the sun’s position along the horizon and their circadian rhythm, or internal clock, to navigate. The Monarch stands out as the sole North American butterfly species that migrates both north and south annually, and it is among the select few insects capable of crossing the Atlantic Ocean. Their majestic presence truly sets them apart, making them some of the best pollinators.
Before Monarchs display their iconic vibrant orange wings bordered in black and adorned with white spots, they undergo a phase of humble existence as caterpillars. The monarch butterfly starts its life cycle as an egg and hatches as a larva. During this stage, the monarch feeds on milkweed plants. The plump and voracious caterpillars have a unique coloring of yellow, black, and white stripes that serve as a warning to predators that they are poisonous and unappetizing. However, after they encase themselves in a cocoon, they become vulnerable to birds looking for food. Hungry birds may taste-test different cocoons until they find the least unpleasant one. Butterflies that survive hibernation and emerge during late summer and early fall must prepare themselves for the long migration ahead. The monarchs that survive the long flight mate between early spring and late summer.
Courtship among Monarchs is a captivating spectacle that unfolds in two distinct phases. It commences with an airborne dance between males and females, but as the courtship progresses, the pair descends to land and remains connected for approximately thirty to sixty minutes. Larvae born towards the conclusion of the mating season typically enjoy an extended lifespan, crucial for their journey south during the winter migration.
While Monarchs consistently return to the same wintering areas, they display remarkable adaptability in their choice of habitats. These majestic butterflies can be spotted in diverse environments, including fields, meadows, conifer groves, gardens, and even some urban areas. Monarchs visiting northern California, for instance, frequently form clusters in eucalyptus trees in locations like Santa Cruz and Pacific Grove near Monterey. These large Monarch gatherings protect the butterflies from cold and rain during the winter. Observations have also noted their presence in the tall eucalyptus trees at the Richmond Field Station, where The Watershed Project’s office is situated.
Presently, the Monarch species holds a near-threatened status, primarily attributed to the diminishing wintering habitats, especially in regions like Mexico. Additionally, the impact of climate change, leading to altered weather conditions, has increased the vulnerability of Monarchs during their annual southward migration. Contributing to the conservation effort, individuals can make a positive impact by planting a butterfly-friendly garden in their backyard. This not only supports the preservation of the Monarch but also allows us to continue marveling at their majestic beauty and resilience.