Monarch butterflies to migrate through Colorado this spring; what you need to know

Yahoo

10-03-2025

DENVER (KDVR) — This spring, be on the lookout for monarch butterflies, as the winged insects make their annual migration across Colorado to Canada.
Millions of black and orange wings will flutter across the U.S. this spring, as the monarch butterflies make their annual 3,000-mile trip from Mexico, their wintering grounds, to Canada. According to the Butterfly Pavilion in Westminster, the migration is more than just a breathtaking sight.
During the migration, the butterflies will carry pollen between flowers, which helps plant reproduction and the wildlife that benefits from those plants.
Butterfly Pavilion data used in study showing 1 in 5 butterflies were lost since 2000
Colorado will reap the benefits of the migration, as the Butterfly Pavilion said the Centennial State lies along the central flyway for the monarchs. The exact number of monarchs that will pass through the state varies year to year. However, the Butterfly Pavilion said numbers are declining.
The population of butterflies that migrate to Mexico for the winter is part of the eastern migratory population. Today, the Butterfly Pavilion said the eastern migratory population has declined by approximately 80%.
While the exact number of butterflies that will travel across Colorado isn't known, the pavilion is working to track and protect monarchs along their route.
Each spring, the nonprofit invertebrate zoo launches the Butterfly Pavilion's Colorado Butterfly Monitoring Network. The community science project enlists volunteers to monitor and collect data on the butterfly population across Colorado.
The data from this program is then used in studies, including a recent one published in 'Science' about the declining butterfly population in the U.S.
The Butterfly Pavilion said monitoring begins in May and lasts through September.
As the monarchs move north, Coloradans can do their part to keep the winged insects safe while also taking in the beautiful view.
The Butterfly Pavilion said monarchs will be seen in parks, gardens, open spaces and along riparian corridors.
'Some of the best places to spot them include nature preserves, butterfly gardens and areas where milkweed and other native wildflowers are abundant. Butterfly Pavilion also has its Discovery Gardens with plants and flowers, including milkweed that attract pollinators, including monarchs during the late spring months,' said the pavilion to FOX31.
In a recent study published with the help of the Butterfly Pavilion, data found that butterfly populations dropped by 22% in the past 20 years. The insect zoo said that 22 species have declined by over 90%, and another 107 species have lost over half their populations.
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During the monarch migration, the Butterfly Pavilion said Coloradans can do their part to ensure that as many butterflies make it to their destination.
The pavilion said people can protect migrating monarchs by planting native milkweed and nectar plants, avoiding the use of pesticides and participating in conservation efforts.
Once the butterflies reach their destination in southern Canada, they will begin the trip back to Mexico at the end of summer, giving Coloradans another chance to see and learn about the great monarch migration.
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