What is this insect?

Hi,

New to this forum. Found this critter on a Northern Red Oak leaf in MA. It's fleshy, clings tightly to leaf (as though it had suction pad feet). Is it larval stage or adult? Larval, I suspect.

https://www.dropbox.com/s/617ea340dxpxa33/11330049.jpg?dl=0
https://www.dropbox.com/s/5ak8x00cidus6n4/11330053.jpg?dl=0

Also, how do I insert an image directly in a post without using a link to some other site? I don't see anything that allows that.

Thanks!