Continuing from part 1, Elias Bonaros did some digging and took these photos of first and second instar Magicicada periodical cicadas on a warm winter day (March 21, 2010).
Now you know what cicadas look like when they’re underground!
Generally speaking the ones with the bulbous abdomens are second instar, and the smaller ones with the less bulbous or not bulbous abdomens are first instar.