Like its lookalike, the Hackberry Emperor, the Tawny Emperor likes to perch high in the trees. It can be distinguished from the Hackberry by the two solid bars on its forewing. One of the bars is broken on the Hackberry Emperor. The Tawny Emperor also lacks spots on the underside and upperside of the forewing.
The Tawny Emperor can be spotted throughout Texas except in the Panhandle and the El Paso area. It is reportedly less common than the Hackberry, but I have found that to depend on the location. In San Angelo, I mainly saw Hackberry Emperors. Here in southwest Houston, I mainly see Tawny Emperors.
In my experience, the Tawny Emperor tends to be less vibrant in appearance than the Hackberry, but there are exceptions as seen in the photos below.
The National Butterfly Center attracts dozens of Tawny Emperors to tree trunks filled with a sap like substance they create. Not sure what their formula is, but you can see the results below.
Similar species: Hackberry Emperor; Empress Leilia
I live in the Panhandle and I see these regularly! I got a great picture of one today.