Overview This summer will be a lot noisier than usual. 17-year Brood X (ten) cicadas are expected to emerge in the billions in every part of the WEMU listening area. The last irruption was in 2004. Periodical cicadas are thought to have evolved the 17-year pattern to avoid predation. They are eaten by nearly anything that can fit them in their mouths, so the survival strategy is to win by sheer numbers. The event will last about two months, beginning in May when the soil warms to 64°F. The nymphs crawl up the trunk of the tree where they molt into the adult form.