Monarch Butterflies in Colorado: identification guide and best places to start

Monarch butterflies definitely occur in Colorado. They are a breeding and migratory passage species here. Most are seen during late summer as adults move south toward Mexico. Small numbers also breed locally during the summer months.

See our state wildlife page for the next step.

Your best odds are along the Front Range corridor from Colorado Springs to Fort Collins. Look in tallgrass prairie remnants, along river corridors, and in city parks that maintain unmowed meadows. Specific sites include the Rocky Mountain Arsenal National Wildlife Refuge, Barr Lake State Park, and the High Line Canal Trail.

See our Monarch Butterflies guide for the next step.

The main monarch window runs from mid August through early October. Peak migration usually hits in early to mid September. A few early migrants may appear in late July, but the bulk comes during the last weeks of summer when goldenrod and rabbitbrush are blooming.

See our state animal guide for the next step.

Monarchs are large with bright orange wings laced with thick black veins. The outer edge has a black border dotted with white spots. The viceroy butterfly is smaller and has a black horizontal line crossing the hindwing. Also, monarchs glide more than they flap, often sailing on thermals.

Adults feed on nectar from flowers like goldenrod, aster, and milkweed. Caterpillars rely exclusively on milkweed species, such as showy milkweed and whorled milkweed. Planting or protecting these natives is the most practical way to support monarchs in your own yard.