The Monarch Highway

The Monarch Highway is busy this time of year. So, keep an eye out while you are driving or outdoors. First, you may only see one, but keep watching, and eventually, you will see them fluttering by in masses. Monarch butterflies are probably the most recognizable and beloved butterflies in the world. Monarchs are currently making one of the most magnificent migrations of any animal in the world. Some travel close to 3,000 miles to their wintering grounds in Mexico. The Upstate of South Carolina along the Blue Ridge Mountains is one of their prime migration corridors and fueling stops on their journey south. This migration is unique because, unlike whales or other large mammals, who have previous generations to learn from and guide them, the monarchs making this migration have no help and are making this trip for the very first time. They are making the same journey that their great-great-grandparents made the previous fall. This ‘super generation’ of monarchs will make this journey south only once in their life. Next fall, it will be their great-great grandchildren’s turn.

A tagged monarch on its journey south, which was tagged by me near Lake Keowee!

A tagged monarch on its journey south, which was tagged near Lake Keowee!
Mallory Maher, ©2022, Clemson University

If you ask an adult or a child to name a butterfly, they will most likely select monarchs. What would a world look like without them? Their numbers are declining year after year. Some researchers estimate that their population has reduced by 80-90% since the 1990s! Their numbers are falling for a variety of reasons. Habitat loss and habitat fragmentation are a couple of reasons that populations are declining. There once was a time where South Carolina and the east coast had vast prairies filled with wildflowers. Today, those prairies have been replaced with forested areas or non-native lawns. Monarchs also face problems in their wintering grounds, which are in the Sierra Madre Mountains in Mexico. Monarchs roost on the Oyamel fir (Abies religiosa) trees. These forests create a perfect microclimate for the monarchs to spend their time in winter. Unfortunately, this habitat faces severe threats due to illegal logging activity, and less than 2% of the original forest remains.

Monarch on butterfly weed.

Monarch on butterfly weed.
Mallory Maher, ©2022, Clemson University

If the monarchs survive the winter, they will start to make their way north from Mexico during the spring. Monarchs lay their eggs on a plant called milkweed, which is a host species necessary for monarchs to complete their development. Many different species of milkweed are native to South Carolina, such as butterfly weed, common milkweed, and swamp milkweed. Monarchs lay their eggs on milkweed for protection because the plant is poisonous, so species of animals cannot eat it. Once their eggs hatch, the caterpillars eat the milkweed, thus making them toxic as adult butterflies. Without milkweed, you cannot have future generations of monarch butterflies.

What can you do to help monarchs? During this time of year, you can provide nectar sources for the migrating monarchs so they have food as they make “pit-stops” on their journey south. Also, having flowers in bloom during the fall will help them out tremendously and give them the last bit of energy needed to make it to Mexico!

For more information on Monarchs, see HGIC Blog You Can Help Monarch Butterflies, and Xerces Society Monarch Butterfly Conservation.

If this document didn’t answer your questions, please contact HGIC at or 1-888-656-9988.

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