Lateral Thinking for Every Day

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Lateral thinking in nature

The 17-year cicada has the longest known life cycle of any insect. In the US large broods of this species appear on time every 17 years. When a tiny cicada nymph emerges from its egg it burrows into the ground, where it lives for 17 years. After this exact time, it waits until the ground temperature reaches 18° C and then emerges in huge numbers. It lives for only four to six more weeks, in which time it eats and mates and the female lays eggs so the long cycle can start again. Why 17 years? No one knows for sure, but it is interesting to note that 17 is a prime number. Cicadas appear to be a delicacy for many predators including birds, mice, lizards and, in China, people. Say the life cycle of the cicada was 12 ...