I photographed these mating Gulf Fritillaries (Agraulis vanillae) in J.N. "Ding" Darling National Wildlife Refuge on Sanibel Island, Florida last July. It is interesting to note that the wings of the mating butterflies are partially overlapping (another picture is here).
Compare the relative positions of the Gulf Fritillaries with those of the mating Eastern Tailed Blues (Everes comyntas) whose only the tips of their abdomens were touching.
The Gulf Fritillary is primarily a southern species; its range extends thru the southern United States into South America and the West Indies.