I have hunted near Manhatten many times. You can find milk snakes, speckled kingsnakes, great plains ratsnakes, bullsnakes, ringnecks, lined snakes, flathead snakes, garter and ribbon snakes, great plains skinks, collard lizards, northern prairie skinks, five-lined skinks, box turtles, red-eared sliders, painted turtles, softshell turtles, american toads, bullfrogs, plains leopard frogs, great plains narrow-mouth toads, chorus frogs, cricket frogs and a few other sp. around the area. My suggestion is to research about the Konza Prairie. This is prime habitat for herps, most of which are named above. You cannot herp on the actual prairie, but there are endless miles of privately owned habitat that is very similar to the Konza. I would look for rocky hillsides, but pay close attn to the hillsides where the rocks are less numerous, but much larger in size. For more information on Kansas herping specifically, go to this webbpage and ask whatever questions you may have:
www.smoky-hills.com/kansas
I hope this helps...