Every 17 years in the eastern US, giant cicadas emerge from underground to mate. Watch for a cicada getting friendly with David Attenborough's ear. From the BBC documentary Life in the Undergrowth.
(there's another video on the sift about 17 year cicadas with great footage, but no Attenborough).
(there's another video on the sift about 17 year cicadas with great footage, but no Attenborough).

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Attenborough pointing out that 17 is prime, and therefor has significant survival benefit as a reproductive cycle length would take more time to explain to the layman then the whole vid, and probably the whole program.