What is this creature?
Walkingsticks, like that in your photo, belong to the insect order Phasmida (also sometimes called Phasmatodea). The species in your photo belongs to the family Pseudophasmatidae. Texas has two species documented for this family. One is Anisomorpha ferruginea, commonly called the dark walkingstick or northern two-striped walkingstick.  The other species is Anisomorpha buprestoides, commonly called Florida stick insect or two-striped walkingstick.

According to W.S. Blatchley's Orthoptera of Northeastern America (1920), pg. 145, A. ferruginea has narrow stripes and is a bit shorter than A. buprestoides, which has broad stripes. Based on the appearance of the stripes in your photo, I'd say you have A. buprestroides.