These brood X cicadas are slightly smaller than the yearly ones in Iowa. The brood X ones are a dark blue with brilliant red eyes as contrasted to the greenish ones in Iowa. Their song is also different, a bit lower and more of an oscillating hum, rather than the buzz saw sound. And, the brood X ones are every where -- they leave an oily stain on the roads where they get crushed and, rather than an occassional shell on a tree trunk, there are hundreds of shells on every tree.