These photos show the Southern Oak Hairstreak (Satyrium favonius favonius). The Northern Oak Hairstreak (Satyrium favonius ontario) had less red on the submarginal band on the underside of the hindwing.

Barton Creek greenbelt, Austin, Travis Co., TX 4/29/2011.

Barton Creek greenbelt, Austin, Travis Co., TX 4/29/2011.

Barton Creek greenbelt, Austin, Travis Co., TX 4/29/2011.

Barton Creek greenbelt, Austin, Travis Co., TX 4/29/2011.