Swarm of Cicadas Takes Aim at U.S.

wetshoe writes "'After 17 years of relative quiet, Mother Nature is bringing the noise. 'Periodical cicadas, a species of the grasshopper-like insects best known for the scratching, screeching "singing" of the males, will emerge this May, filling forests in more than a dozen states. Almost as abruptly as they arrive, they'll disappear underground for another 17 years.' The article also talks about areas in the Mid-West where 17-year June Bugs sometimes overlap with 13-year June Bugs. I remember as a child one such time, you literally couldn't walk anywhere without stepping on them, they were everywhere. Reminded me of a biblical plague."

Comments

Not June Bugs

[Anonymous Coward]

Cicadas are not June Bugs .

Maps

[DustMagnet]

This website has a nice table showing the years and locations of cicada broods. There are maps of the range, include one for 2004.

Interestingly, they don't list any 13-year broods in 2004 (unlike CNN).

Prime numbers

[CalCudahy]

I remember reading an interesting essay by Stephen Jay Gould on why these species that only emerge periodically do it at prime number intervals. The problem is that they have to swarm in such huge numbers to overwhelm any predators and multiply rapidly. To prevent a predator from evolving to depend on their "blooms" and wipe them out when they emerge, they only do it at prime number intervals. That way a predator would have to multiply in the same time interval and not some fraction of it. If it was 12 years a predator could multiply every 2,3,4, or 6 years and have a chance of feeding just when the cicadas were blooming. It's a lot less likely that a predator will multiply at only 17 years at the same time as the cicadas.

There are also species of bamboo that periodically produce tons of seeds to reproduce, but on the order of every 70 years. These too only do it on prime number years.

Who knows if he was right, but it is a cool theory.