These were quite common at Bentsen Rio Grande State Park during this trip, and I also saw several at this location. (They were so common, I almost forgot to take photographs of them!) Length measured in place--25 mm without the ovipositor.
Eric Eaton has suggested a similar specimen from southern Texas may be Chestnut Short-winged Katydid, Dichopetala castanea:

See also SINA, and compare this one from Hidalgo County at the same time as the photo from La Lomita:


This photograph was taken during a field trip as part of the 2006 Texas Butterfly Festival in Mission, Texas. (Photo taken at the Rancho La Lomitas preserve. Many thanks to the Trevinos for their hospitality.)