This is Florida’s state butterfly! A lovely and distinctive black butterfly with narrow yellow stripes on its elongated wings, the zebra longwing (also known as the zebra heliconian) is native to peninsular Florida and south Texas in the US (sometimes migrating into states further northward). They also live all over South and Central America.
Heliconius charithonia butterflies roost gregariously in groups of up to 60, forming large clusters and often returning to the same place to roost each night. Their wingspan is about 8 cm across.
Unusual for butterflies, adult zebra longwings eat pollen as well as nectar; the pollen allows them to synthesize toxic chemicals which make them unpalatable and/or poisonous to potential predators (hence the yellow and black, aposematic coloration). The caterpillars, which are white with black spots and spikes, feed on passionflower.
Butterflies rarely allow me close enough to get a photo with my macro rig, so this was a welcome surprise.