17-year locusts and evolution

There are many species of locust that have differing years before reaching maturity, most of them 'normal' in a 2 to 8 year range with some flux back and forth.Either from these more 'normal' species or similar ancestors, the periodical cicadas have evolved: 7 distinct species -- 4 that emerge in 13 year cycles (one recently discovered) and 3 that emerge in 17 year cycles -- and it appears that each of the 17 year species is related to one of the 13 year species, thus parallel evolution repeating a pattern of increasing cycle time.The fact that both of these long periods are prime numbers has been one of their most facinating aspects. Of course this makes it very difficult for a predator to match the periodicity, thus allowing the large swarms to emerge and overwhelm the predator base, ensuring sufficient mating occurs in the few days the adults live for the species to survive. Last thing I remember reading was that the scientists believe that the flow of sap in the roots tells the nymphs when to emerge.see University of Michigan Museum of Zoology, Insect Division, Cicada Webpage (click)for a good article on each of the species involved.My brothers and I collected bugs as kids growing up in Ann Arbor a number of 17 year cycles ago, and the 17 year cicada was in the collection.

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we are limited in our ability to understand
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Your neighbor also knows that he cannot collect good sap during the winter or late into the summer, that the best flow is when you have freezing nights and thawing days. You could measure the sap flow on an annual basis and know when spring arrives.The emergence of the nymphs seems to be temperature driven once the correct number of years have passed, so it is not on the same day of the year. That takes care of the weather patterns and temp cycles.

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we are limited in our ability to understand
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The idea of predation driven must take into account the numbers of cicada predators, which are just too numerous for one to make a difference.Consider, however, that all life cycles have some ups and downs, cyclic rhythms in populations. Thus any life cycle that matches those cycles is at hazard, while one that misses every now and then and has a boom year gets ahead. Prime numbers would do that in a general pattern system.

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we are limited in our ability to understand
by our ability to understand RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}