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Old 2021-05-05, 18:13   #67
Uncwilly
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Quote:
Originally Posted by Dr Sardonicus View Post
Here's a "topper." Some periodical cicadas spend 13 years underground. And 13 is another prime number!
If I understood the show that I heard correctly...
What is happening is a 4x +1 issue. At times weather/tree growth patterns will mess with he cicada's timing. Parts of broods will emerge off the normal cycle if trees "wake up" and then the weather "puts them back to sleep". The little buggies are drinking the trees' vital fluids. If they emerge off schedule they do so 4 or 8 years early. The first year is a given (they don't count that.) Then every 4 cycles of the tree, they count.
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Old 2021-05-07, 01:40   #68
Dr Sardonicus
 
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Quote:
Originally Posted by Uncwilly View Post
If I understood the show that I heard correctly...
What is happening is a 4x +1 issue. At times weather/tree growth patterns will mess with he cicada's timing. Parts of broods will emerge off the normal cycle if trees "wake up" and then the weather "puts them back to sleep". The little buggies are drinking the trees' vital fluids. If they emerge off schedule they do so 4 or 8 years early. The first year is a given (they don't count that.) Then every 4 cycles of the tree, they count.
You might want to look at The 2021 Periodical Cicada Emergence (Brood X) (which also has links to "stragglers"). The striking thing about periodical cicadas is the extreme synchrony of each "brood." Most "stragglers" in a brood's area emerge one year "off cycle" (before or after), with four years "off cycle" (before or after) being next most common.

In addition, this University of Michigan page, even though it was last updated ten years ago, has some interesting information on the seven Magicicada species. There are "species pairs" of 17- and 13-year cicadas which seem to differ mainly in geographic distribution and length of development. The 13-year "broods" are generally more southerly than the 17-year broods.

Also, Answers to some common questions about periodical cicadas may be of interest.

If those aren't enough, the Cicada Mania site will probably fill the gap.
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