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

Your best odds are along the coast and in open habitats. Cape Cod, especially the Monomoy National Wildlife Refuge, and the islands of Martha's Vineyard and Nantucket are reliable spots. Inland, the Great Meadows National Wildlife Refuge in Concord and the Oxbow National Wildlife Refuge in Ayer see consistent monarchs. Closer to home, check group gardens, parks with milkweed patches, and roadsides with goldenrod. During migration, they concentrate at coastal roost sites before crossing open water.

Monarchs arrive in late spring for breeding, but the main show for spotters is the fall migration from late August through October. The peak usually falls in mid to late September. On warm, sunny days with a light north wind, you can see dozens moving south. The breeding season from June to early August is less dramatic but offers chances to see eggs, caterpillars, and fresh adults on milkweed.

A monarch is large, with a wingspan of 3.5 to 4 inches. Its wings are bright orange with thick black veins and two rows of white spots along the black wing borders. The key trick: monarchs glide with wings held in a shallow V. The viceroy butterfly is smaller, has a black line crossing the hindwing, and glides flat. In Massachusetts, you will most often see monarchs alone or in small groups, not in large aggregations like in Mexico.

See our state animal guide for the next step.

Monarchs need milkweed for breeding and nectar plants for fuel. Look for them in fields, meadows, roadsides, salt marshes, and gardens that have common milkweed, swamp milkweed, or butterfly weed. They also feed on asters, goldenrod, and blazing star. Coastal dunes and scrublands are excellent during migration. Backyards with native plants can host them too, especially if you have a patch of milkweed.

Monarchs move best on sunny, warm days with temperatures above 60°F and light northwesterly winds. After a cold front passes, migration often picks up. They stop flying in rain or heavy clouds. In the fall, a few days of clear, cool weather can push large numbers south. Mornings are good for seeing them nectaring to refuel, while afternoons are better for watching migrants cruising south.