Looks like it's probing the wood with its beak -- I count six legs and one extra thingie under its head. It's perfectly lined up with the shadow of the leg, so it took me a while to sort things out! I didn't know whether adult cicadas feed. Turns out they do -- see here, for example.
Thanks for your comments. I took several images as this guy moved around while feeding, but this is the best one (of course). The other ones were more silhouette (sp?).