The ranges of the 17 & 13 year Periodic Cicadas don't really overlap, so the strategy isn't to avoid competition with other cicadas. It's believed that the prim

The ranges of the 17 & 13 year Periodic Cicadas don't really overlap, so the strategy isn't to avoid competition with other cicadas. It's believed that the prime number periodicity is to avoid the life cycle periodicity of predators. Besides, in areas where different cicadas overlap, they spend something like 99.9% of their time underground consuming the same food resource, alongside the non periodic annual cicadas. Competition between cicadas doesn't seem a major issue.