Header photo: By Captain-tucker - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=6957753 Male Monarch on Buddleja.
This time of year in coastal Georgia, many butterflies will be passing by on their way south. Some are headed to Florida, while some will continue all the way to Mexico! Of the several orange butterflies one is likely to see in the area, the Monarch can be distinguished by its black border with white spots. This could be tricky though, as the Viceroy has very similar field marks, so to differentiate between the two look for a black band going through the orange on the hind wings of the Viceroy and a more erratic flight pattern. Monarchs will move more slowly and “sail” more as they fly.
These individuals are not, however, the same ones that flew north. In fact, the butterflies we see in the fall months are completing a journey started by their great grandparents in the spring of the same year. During their journey north, the monarchs will reproduce and die 3 times. Then, the 4th generation will cover the most ground, covering the entire southward migration alone, sometimes averaging 50 miles per day. This same generation will be the first leg of the northward trip the following Spring. That an incredible migration for something weighing less than 1/5 of an ounce!
There are a few wintering locations, California, Mexico, and Florida, and some in the Caribbean. The ones we see in Georgia winter in Florida, the Caribbean, and some in Mexico. The ultimate goal in this southward movement is to find warmth for long enough to begin the cycle again the next year, and they have particular preferences when choosing a spot to roost for this nearly 5 month period. In the case of their Mexican wintering habitat, the preference is very specific. The monarchs prefer an area 10,000ft. high in the mountains totalling about 60 square miles. Of the 100 million individuals that migrate south each year, most of them are headed to this small area. Once they arrive, they carefully choose to situate themselves on the southwest facing slopes of the mountains, preferably on the largest trees, which retain warmth better than smaller ones. The butterflies’ arrival, which happens in large waves, commences the Day of the Dead holiday for the indigenous Mazahuas, because they believe the butterflies contain the spirits of their ancestors.
This area was protected by the Mexican government in 1986, but they still face a large challenge in preventing illegal logging. After the loggers select and remove the timer they want, they often burn the area from which they’ve harvested.This degradation of such a vital habitat currently poses the greatest threat to the monarch butterfly.
How they know where to go, these 3.5 inch insect, after starting their lives in locations as far as Canada, is still a mystery. The cues for departure are likely things like daylight, sun angle, dying vegetation, and temperature. As for navigating, hypotheses surround ideas like using sun angle or Earth’s magnetic field. To learn more about the instinctual basis of their southward migrations, Dr. Chip Taylor* moved monarch butterflies from Kansas to Washington D.C. and set them free to see what they would do. They were outfitted with tags, which once recaptured would reveal movement patterns. The butterflies, if still in Kansas would have only needed to fly straight down south to Mexico, and that’s what they initially did after leaving D.C. But after a few days, they somehow realized they were off track, re-oriented, and altered course to the west then south to Mexico. So, it seems that the appropriate path is not simply “hardwired,” but somehow detected and chosen.
So what can you do to help Monarchs? The easiest thing is to plant a few things in your garden. Specifically, milkweed, as the monarch caterpillars are laid exclusively on this plant and will feed on its leaves. Milkweed in your garden will help them get north in the spring, but for the fall, the big necessity is nectar. The nectar from flowering plants give them the energy they need to cover those long distances migrations, so make sure you have some plants that will be flowering in early fall.
Suggested native Georgia milkweeds are:
Download this brochure for identifying the butterflies and caterpillars you see in Georgia and the plants they need.
retrieved from MonarchWatch.org
Caterpillars on milkweed
Photo By Engeser – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=3435697
Nymph in chrysalis just prior to emerging
Photo By Hectonichus – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=12620104