Southern New England Coastal Plains and Hills

Monarchs pass through on fall migration south

October 3, 2026

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s recorded 195 times in the past 60 days with the most recent observation on 2026-10-02.¹ The migratory population is currently passing through the region during its fall migration toward Mexico, with peak activity in New Jersey expected around October 4.² Though the species was proposed for threatened listing, it remains unprotected federally, with population recovery dependent on preserving milkweed and reducing pesticide exposure along the migration route.¹

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Monarch butterflies pass through on their fall migration

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butterflies were recorded 51 times in September 2026 across the region, with sightings continuing through late September. These are the migrating generation heading to overwintering sites in Mexico; in Michigan, peak migration occurs around mid-September, which aligns with observations here. The species is listed as Proposed Threatened under the Endangered Species Act.