Gulf Fritillary Butterfly
Gulf Fritillarys migrate by the thousands up St. Joseph's Peninsula in late September and early October.
The Gulf Fritillary (wikipedia) is commonly seen in parks and gardens, as well as in open country. Its range extends from Argentina through Central America Mexico, and the West Indies to the southern United States, as far north as the San Francisco Bay Area on the west coast. It is occasionally found further north in the US.