you can use oak, popple, birch, iron wood, maple, and hickory. I know your dissapointment when you find a peice that you like, but it will kill any frog. Also don't use any green wood(still alive) as even oak is toxic when it's green. Best to find down branches, 1/2 rotted, or barkless pieces. You can scrub the rot with a rock and get a nice polished piece out of it.