March 17: Spring has warmed the mountains of Michoacán in the State of Mexico. As I write this, the noon temperature in that alpine forest is 74 degrees Fahrenheit. The monarch butterflies that have been hibernating in tall fir trees have started leaving their mountain roosts to voyage north on their yearly migration in search of milkweed host plants for their young. By the end of March, all of them will have left Mexico to journey north.
As early as this January and February, Monarchs have already been sighted on the Gulf Coast of Alabama, Mississippi, and throughout much of Florida. They will be in the Georgia Piedmont soon, and as you read this, fragile orange wings are flapping and fluttering against air currents to make their way here. By the time the Monarchs have reached Beech Hollow in late March and early April, the journey will have been roughly 1500 miles.
Why do they migrate? The timing of the butterflies’ northward migration follows the seasonal availability of the larval host plants that monarchs need to feed their young. They will migrate only as far north as the milkweed grows. However the timing of the southward migration has the insects traveling well ahead of cold winter temperatures that they cannot survive. And as they travel south during the late summer through the fall, there are still plenty of nectar plants for them to forage on to fuel their journey to the alpine forests in Mexico. How’s that for travel planning? From the summer range in southern Canada to Mexico’s alpine forests, the total journey averages 2500 miles.
Rough timing of Monarch migration stops: When the female Monarch arrives in the southern United States between February through April, she will lay her eggs, and only upon Milkweed plants. Her caterpillars feed on the Milkweed, grow, pupate, and hatch. It takes anywhere from 4-7 weeks for the second generation of butterflies to mature enough to take up this generational relay.
This second generation of new Monarchs flies into the northern United States and Southern Canada in late spring. When the butterflies arrive, the females lay the eggs of generation number three on Milkweed plants.
In August and September, Monarch generations three and four will start flying southward, retracing their flights back to the mountains in Michoacán and the State of Mexico. When the butterflies arrive, they overwinter in large fir trees and wait for the return of spring.
Habitat needs: A garden with native plants which provide nectar for the adult butterflies is important. Even MORE important for Monarch butterflies is the availability of their larval host plant: Milkweed. Supporting their full life cycle by providing host plants for their caterpillars will ensure the return of these intriguing insects year after year. Milkweed species that are recommended by the GPCA (Georgia Plant Conservation Alliance) and native to the state of Georgia are:
- Clasping Leaf milkweed, Asclepias amplexicaulis
- Poke Milkweed, Asclepias exaltata
- Pink Milkweed, Asclepias incarnata
- Butterfly weed, Asclepias tuberosa
- and Whorled Milkweed, Asclepias verticillata
Please Provide Water, everyone needs clean water, even insects. A ceramic plant saucer with large pebbles or a sand ramp in it will allow butterflies to approach the water without being drowned.
Minimize use of toxic chemicals, such as pesticides, which can sicken or kill unintended, or “non-target,” wildlife. If you must use a pesticide, be aware of your larval host plants and other pollinators, apply pesticides carefully to avoid destroying your beneficial insects.
Websites with additional information:
Annual generational lifecycle:
Western Monarch Information: