Where do butterflies go in the winter?

As autumn fades into winter, so do the bright colors of the butterflies who danced across our summer gardens and fields.

But these creatures aren’t gone. They’re simply on the move.

Across North America, butterflies will spend the late summer and early fall on epic migrations across the continent. Yet as you see their delicate forms floating overhead or stopping for a rest on a nearby flower you may ask yourself … 

Where exactly do these butterflies go for the winter?

Butterfly migrations are some of the most epic journeys in the animal world

Butterflies pollinate flowers and are valuable indicators to the health of our ecosystems. But when frost creeps in and their host plants die out, most butterflies can’t survive the cold. That’s why some will migrate incredible distances to find warmth and food.

Many will head for the mild winter climates of the American South, Gulf Coast, coastal California or central Mexico, following invisible routes that have existed for millennia. Along the way, they pause to feed and lay eggs on specific host plants. These eggs will hatch the following spring. Their descendants will follow new blooms and the warmth of the sun ensuring that generations to come can continue the voyage even if their parents cannot.

And while many North American butterfly species undergo some truly impressive migrations, four species stand out above the rest.

Monarch butterflies

No migration is more famous than that of the monarch butterfly. 

Each fall, these iconic orange-and-black insects set out from as far north as Canada and the northern United States, flying up to 3,000 miles to their winter sanctuaries. 

Eastern monarchs, living east of the Rockies, will usually migrate down into the Sierra Madre mountains of central Mexico. Meanwhile, the other population, Western monarchs, usually wind up in the forests of coastal California. 

The last generation of monarchs born in the North will be the ones to undergo this epic trip. This generation, deemed the “super-generation,” is built for travel. They can live up to nine months, nearly eight times longer than a typical monarch. 

Upon arrival, these super monarchs converge in the forests of California and central Mexico, carpeting trunks and branches so densely that the combined weight of their tiny bodies may actually break tree limbs. 

Come spring, the original migrants have died off. But they leave behind eggs that will hatch, grow and start the long trek back north. 

While individual monarchs are talented travelers and are capable of traveling up to 50-100 miles a day, it can still take 3-4 generations to complete the trip back north.

Painted ladies

While monarchs are perhaps the most recognizable, painted ladies hold the record for the longest butterfly migration on Earth. Some global populations cover up to 9,000 miles a year, migrating from the northern reaches of Europe down into Western Africa. 

In North America, painted ladies undergo a slightly less intense journey. When the cold begins to set in, they usually migrate from Canada and northern states down toward warmer regions in Mexico. 

Unlike monarchs, their migrations are unpredictable. They don’t migrate every year, and their migrations may be triggered by heavy rainfall. 

In wet years, when wildflowers erupt across the northern landscape, millions can take to the sky at once. During California’s 2019 “superbloom,” millions of painted ladies swept across the state. 

Red admirals

Friendly, curious and found across the globe, the red admiral is a butterfly that will often flutter near, or even land on, people. Its black wings, streaked with red-orange bands and tipped with white spots, are a familiar sight in gardens and along forest edges.

Northern populations will travel hundreds of miles south, some reaching Texas, and some heading as far south as Central America. Unlike monarchs, red admirals travel and continue to breed year-round in warm climates, allowing them to maintain a steady presence through the seasons. 

But when northern conditions warm and new flowers bloom they will head north again.

Cloudless sulphurs

These pale yellow butterflies are easily spotted as they drift low across roads and meadows. During the summer, cloudless sulphurs can mostly be found throughout the Eastern United States and even into Canada. But as autumn advances they head south into Florida and other areas of the southern United States.

Along the way, females lay eggs on host plants like the senna so their offspring can carry the migration forward. In late summer, you may see these bright insects fluttering among gardens and meadows as they rest and prepare to continue their southward journey. 

These butterflies migrate slowly, over multiple generations and often right at eye level. This makes their migration one of the easiest ones for people to observe. 

The threats butterflies face on their journeys

Butterflies may escape the cold, but they still face other threats as they migrate. Recently, butterflies are finding these ancient trips harder and harder to complete each year.

Many of the areas that once offered rest, nectar and safety for butterflies during migration have been erased as development has paved over forests and meadows. Meanwhile, host plants such as milkweed — which is vital for monarch reproduction — have vanished by the hundreds of millions. Without host plants, butterflies have nowhere to lay their eggs and their caterpillars have nothing to eat. 

Shifting weather patterns are also disrupting how monarchs time their migrations. Temperature is an essential cue that many butterflies rely on to time their journey But as temperatures stay warm later and later into the season, butterflies are delaying their migration. This can result in them departing too late, leaving them vulnerable to cold and making the completion of their trip much more difficult. 

Another threat to butterflies is neonic pesticides, which are poisoning the very flowers and habitats that butterflies depend on. These chemicals linger in soil and can move into the nectar and pollen of a plant, impacting brain activity when ingested and silently weakening or killing any pollinators that feed nearby.

For creatures whose survival depends on timing, flight and delicate connections between plants and weather, these pressures can disturb the migrations that have persisted for millennia.

How to help butterflies complete their ancient migration

The good news is that we can help butterflies finish their trips.

Even small patches of native habitat in yards, on balconies and beside roads can provide essential rest areas for migrating butterflies. By planting host plants and nectar-rich native flowers, you can provide areas for butterflies to feed, rest and reproduce.