See here

Those are impressive photos. Unfortunately, there is not a definite statement that they were taken in Hidalgo Co., TX. It is merely implied by the photographer's address.

University Dr. & U.S. Hwy 281,
Edinburg, Hidalgo Co., TX
October 19, 2004 (B Bouton)

Plus, I've seem them there with my own eyes... Mike

These were abundant on shrubs around Lamar Junior High School in McAllen, Texas (Hidalgo County), when I was a student there, in the late 1950s. None of us knew what they were, but we discovered that it was safe to pick them up by the scary-looking "thorn," and then they would release a stream of clear liquid (you can imagine the giggles). Boys would try to make them do this on the girls, and they were occasionally smuggled into classrooms to be released into someone's desk, purse, or other useful location. One particular shrub (I don't know what it was, either) had more than others.

The study of local nature had no part in the curriculum (our teachers didn't know any of the local birds, let alone bugs) so it was years before I even knew they were treehoppers.