This is Proxys punctulatus aka The Black Stink Bug. It can be found in eastern North America up to North Carolina and west as far as Texas and Oklahoma. Heading south, you can find this particular shield bug throughout Central America and into South America to Brazil.
P. Punctulatus somewhat unusual because it feeds on both plant and animal material. Not many shield bugs/stink bugs have that varied of a diet.
The standout fact for me is that this species of Pentatomid lays its eggs individually or in pairs – scattering them over a larger area. All other known members of this family lay their eggs all together in a single group. I would be interested to know if this is helpful as far as competition of food for the nymphs, or on the other hand, if it is detrimental because there is relative safety in numbers.
PS -That is a thorn behind the insect. I was surprised to see so many plant species in Costa Rica covered in thorns. One tree, we were told, only has thorns on its trunk until it can grow thick enough for the peccaries not to be able to eat it. It will then loose its thorns and looks like a normal tree. Interesting!
Also, if you or anyone you know appreciates the important role of arthropods and would like to get involved on a deeper level and support my photography and conservation efforts, please visit Patreon.com/KarlaThompson
The pollinators and I thank you!
Nikon D3x, Nikkor 200mm macro, ISO100, 1/60, F9, three diffused SB200 flash heads, tripod