In the second book Subterranean Threat the Genshees ventured to the surface in airships with cloaking ability and force fields which allowed them to secretly observe the governments of Earth. Only in discrete instances were they allowed to interfere with the Earth's governments.
In Rise of the Reptilians the Genshees revolt against their own Ecclesiastic Benefactor, come out of their underground cities and declare war on the governments of Earth. The fate of the Earth is held in the microchips implanted in the bodies of two earth men. They have to make it to a CIA complex in Saint Louis where the chips can be removed to reveal the formula for eradicating the Genshees from the face of the Earth.