Gulf fritillary may be mating
This is right beside the San Antonio River. I found it interesting because I believe there is a little butterfly head in front of it, making me think they may be mating. Also, this is the first photo I've taken with what looks like golden/shiny vertical lines on the wings that may be the place pheromones are transmitted as mentioned in the species literature. You must zoom in on the photo to see these lines better.
. Further research has confirmed that the glitter-like lines are only on males, and males have a longer abdomen than females. The photo above is a male.
The Gulf fritillary or passion butterfly is a bright orange butterfly of the family Nymphalidae and subfamily Heliconiinae. It was formerly classified in a separate family, the Heliconiidae or longwing butterflies, and like other longwings this species does have long, rather narrow wings in comparison with other butterflies.