Butterflies are more than a fleeting splash of color across Colorado’s skies – they are vital players in ecosystems and sources of endless fascination.

From the elegant Monarch, which travels thousands of miles, to the lesser-known butterflies frolicking through alpine meadows, Colorado’s butterfly season, from May through October, offers a spectacular display of nature’s beauty and resilience. Understanding these delicate dancers and their seasonal patterns may deepen your appreciation of their role in pollination and inspire you to help protect their fragile habitats.

Butterfly season in Colorado

From May through October, native Colorado butterflies emerge and migrate, both northbound and southbound.

Butterfly species in Colorado

Colorado is home to about 250 butterfly species and four times as many species of its less-colorful cousin, the moth, according to the Colorado Department of Agriculture.

Some of these butterfly species never leave, but others, like the Monarch and Painted Lady, may travel thousands of miles, hatching offspring along the way to carry on their legacy and finish their journey. Colorado’s butterflies are as unique as they are beautiful, and their remarkable journeys have inspired celebrations and traditions for centuries.

What butterflies are in Colorado?

Although the Monarch butterfly is probably the most recognizable butterfly in Colorado with its orange wings the resemble stained glass, hundreds more flutter through our backyards and the state’s alpine wildflower fields, said Shiran Hershcovich, a lepidopterist with the Butterfly Pavilion in Westminster.

The Painted Lady displays brown and orange colors and a subtler pattern than the Monarch, while the (male) Tiger Swallowtail shines with its yellow body and black stripes.

Colorado’s state butterfly, the Colorado Hairstreak, has harmonizing colors of purple and orange.

The Cabbage White butterfly, the most abundant butterfly in Colorado, looks like a bride dancing among flowers on her wedding day.

Among the lesser seen butterflies is the elusive Uncompahgre Fritillary, so seldom spotted in its native habitat on Uncompahgre Peak, one of Colorado’s majestic 14ers on the Western Slope, that it is considered endangered.

A butterfly’s life cycle and migration

Butterflies are part of the insect order Lepidoptera, meaning scale wing. Characteristics include:

• Scales, which are modified hairs, cover the wings.
• Proboscis, a long, tubular mouthpart.

Butterflies undergo metamorphosis in four life stages: egg, larva, pupa and adult.

Monarch butterflies migrate over multiple generations because the summer generations of the Monarch butterflies only live 2-3 weeks. As they travel north, they lay eggs and die. Those eggs hatch, feed and continue the journey, happening many times throughout the Monarch’s several thousand-mile migration.

“The Monarch is probably the most iconic of all the butterflies,” Hershcovich said. “Colorado is a very interesting place to understand the Monarch migration path because we are not on its traditional migration path but rather the dividing point.”

The Monarch butterfly migration through Colorado

In the United States, there are two types of migratory Monarch butterfly populations: the Eastern Monarch and Western Monarch.

“Generally speaking, the Eastern Monarch migrates east of the Rockies to the forests of central Mexico, and the Western Monarch spends winters on California’s coasts,” Hershcovich said. “Because the Rocky Mountains is that dividing point, we see both eastern and western Monarchs.”

Monarch migration in Colorado happens in early summer and then again in September and early October. Once they arrive at their warmer overwintering location, that “winter” Monarch generation can live for up to nine months. However, scientists have noticed that changing climates have become more taxing on these butterflies, making it harder for them to survive, Hershcovich said. (Read how you can support the habitat and survival of the Monarch butterfly and other pollinators in Colorado later in this article.)

“The Monarch migration has been tracked for centuries,” she said. “And the migration in different regions is closely tied to celebrations, like Día de Muertos (Day of the Dead), which represents the returning souls of our loved ones.

“I find it so beautiful that we’ve found that inspiration in butterflies.”

What other butterflies migrate?

Besides the Monarch butterfly, the Painted Lady also migrates through Colorado.

“Migration is an impressive strategy developed by the butterfly to cope with winter, which is very difficult for insects because they can’t produce any body heat,” Hershcovich said.

But not all butterflies migrate.

Monarch butterflies, like the ones Hershcovich grew up with in Panama, never leave because they do not need to move to warmer locations in the winter – as there is no winter.

Colorado butterflies that stay here for the winter have other methods of surviving. The Tiger Swallowtail spends its winter in diapause in its chrysalis – a sort of hibernation – and emerges to feed as an adult during Spring’s warmer temperatures. The Mourning Cloak butterfly spends the winter as an adult, hiding in the woods.

“They (Mourning Cloaks) are one of the first butterflies we see flying around in Colorado every spring,” Hershcovich said.

How you can support and protect the Monarch and other Colorado butterflies

Educating yourself and raising awareness about butterflies can be crucial for their preservation. The Monarch butterfly, for example, is currently a candidate for protection under the U.S. Endangered Species Act.

Hershcovich and Amy Yarger, the Butterfly Pavilion’s senior director of horticulture, offer six tips for supporting butterflies and other Colorado pollinators:

1. Plant a diversity of native plants.

Native pollinators have adapted over generations to the plants that originally grew in Colorado. Exotic plants don’t offer the same ease of access and enticement for native pollinators like the butterfly. Think about planting native plants like the Rocky Mountain Bee Plant and Rubber Rabbitbrush.

Milkweed is essential for the survival of the Monarch butterfly.

The female Monarch butterfly lays eggs on the underside of milkweed leaves, a poisonous plant to butterfly predators. When the caterpillar hatches, it feeds on the milkweed leaves. The toxins it gets from the plant stay in its body and protect it into adulthood.

The Colorado Native Plant Society and Colorado State University Extension have great resources on native plants and pollinators.

2. Extend the blooming season.

Pollinators in Colorado may forage from March through November. Plant early bloomers, such as small bulbs, lilacs and chives, to help pollinators. Late bloomers like Rabbitbrush and Goldenrod can also help in the fall.

3. Provide trees, shrubs and groundcovers for shelter.

A layered garden, with plants of different heights, creates a safe place for pollinators. Leaving your garden standing in the fall and winter also provides a niche for pollinators to continue their life cycles.

Groundcover is also important year-round. Pollinators use leaves that fall to the ground to hide or diapause during the winter.

Butterflies often roost in trees or shrubs overnight. Other plants serve a “double duty,” providing shelter and food simultaneously.

4. Avoid pesticides.

“Butterflies are insects too, and pesticides can affect them,” Hershcovich said.

5. Leave wild creatures alone.

The beauty of a Monarch and other butterflies might tempt people to catch one, but Hershcovich encourages people to observe them only from a distance.

“You don’t want to mess up their cues and environment,” she said. “This could confuse them and mess with their sensitive calibration systems, which help them migrate.”

Visiting a butterfly winter migration location is a great way to observe these beautiful insects in mass numbers. You can also visit a butterfly pavilion like the one in Westminster or at the Gardens on Spring Creek in Fort Collins to observe domestic butterflies.

The butterflies at these pavilions are not “wild” but come from sustainable farms and are raised for education.

6. Become a volunteer ‘community scientist’ by participating in butterfly counts.

Like bird counts sponsored by the National Audubon Society, community members can help state scientists obtain a more accurate account of Colorado’s butterfly population’s health by joining the Colorado Butterfly Monitoring Network.

“We are always recruiting volunteers to become community scientists, trained on recognizing and counting butterflies,” Hershcovich said.

Volunteers observe and record butterflies in open spaces and parks during different times of the season. Their findings shape conservation decisions.

“It’s a great way to get outside with a purpose,” she said.