Common Sootywing (Pholisora catullus)
Although this species does occur in parts of Louisiana, I have not seen it here.  These photos were taken out of state and they are only here to show what the species look like and that they should be in a list of Louisiana butterflies.
Common Sootywing
Clifton Park, NY, June 21, 2006
Common Sootywing
Clifton Park, NY, July 11, 2012