Most cicadas go through a lifecycle that lasts from two to five years. Some species have much longer lifecycles, such as the North American genus, "Magicicada", which has a number of distinct "broods" that go through either a 17-year, or in some parts of the region, a 13-year lifecycle. The long lifecycles may have developed as a response to predators, such as the cicada killer wasp and praying mantis. A specialist predator with a shorter life cycle of at least two years could not reliably prey upon the cicadas. An alternate hypothesis is that these long lifecycles evolved during the ice ages so as to overcome cold spells and that as species co-emerged and hybridized they left distinct species that did not hybridize having periods matching prime numbers.