Pretty sure this thorn hopper is in the genus Umbonia. These lovelies are quite common.
This photo shows an 8-9mm Costa Rican trap-jaw ant with her jaws in the open position. Her genus is Odontomachus. If you stretch or enlarge the photo, you can see the tiny setae arrayed along the inside of the jaw. Her jaws will slam shut if these hairs come into contact with prey. I frequently see these ants (as well as another species of trap-jaw) in the forest. They move slowly by ant standards and are relatively easy to photograph.
I'm pretty sure this is one of the 15,000 species in the family of Buprestidae. About 8-9mm IIRC and found at La Selva Biological Station. You can see why the common name for these is "jewel beetles."
