These are lab-reared mantids, but their ancestors were collected in New Jersey, near Princeton University in a field where both T. sinensis and T. angustipennis existed.
How do you tell them apart? The differences are subtle. Angustipennis is a bit more slender than sinensis, the green borders of the wings are narrower, The colors are slightly different in both green and brown forms. Sinensis green is a little bluer and sinensis brown is darker and a little more yellow. Angustipennis has an orange spot bordered in black between the forelegs (used in threat display), and sinensis has yellow, instead of orange. The egg cases are very different, that of sinensis being large and puffy, and that of angustipennis being flattend with very little foam material.