It’s been a very long 17 years for Brood X, our resident periodical cicadas, but they have finally emerged and started to take over D.C.
Periodical cicadas come on the scene in our area every 17 years. When still in their exoskeletons, cicadas are called nymphs. When they first shed their exoskeletons, they look like fragile newborns and are referred to as teneral cicadas:
Just a few hours after they emerge from their exoskeletons, their skin hardens and turns black and their wings inflate. They are now officially adults — they grow up so fast! (If you want to study up on the different phases of a cicada’s life cycle, The Washington Post has a useful explainer.)
Cicadas as tourists
The cicadas have shown up at all of the top tourist places in D.C.
Cicadas as food
Cicadas make tasty treats, loaded with fat and protein for any animal that eats insects.
Parts of a cicada
The red eyes of the cicadas make them easily identifiable. (Interestingly, while periodical cicadas have red eyes, annual cicadas that visit us each summer typically have black eyes.)
But if you look closely, you can also see three tiny ocelli (simple eyes) on the top of their heads, which allow them to see upward.
Cicadas have two pair of wings. They are good but fairly clumsy fliers.
Cicadas have six legs of equal length. The legs aren’t good for hopping but are excellent for clinging on to things.
Male cicadas have membranes called tymbals on either side of their abdomens. These vibrate, producing their distinctive call, which the males use to attract a mate.
The newly-emerged cicada climbs to a vertical surface, then bursts out of the back of its exoskeleton, leaving most of it intact.
The hole that the cicada makes when emerging from the exoskeleton gives a view inside, where there is a fascinating compartmentalized structure.
Cicadas vs. people
Kevin Wolf has been documenting the epic work of people confronting the cicadas.
In a few short weeks, their mating frenzy will end and they will all be dead of either old age or predators or human actions, and their offspring will live under the roots of trees until it is time to re-emerge in 2038. It’s a magical process, so it’s no wonder that the genus of cicadas is Magicicada.
And why do we have to wait 17 years until the next time Brood X emerges?
Well, nobody knows exactly why, or how the cicadas manage to count to 17. But there are two types of periodical cicadas — one with a 13-year cycle and our Brood X with a 17-year cycle. Notice that 13 and 17 are both prime numbers, which guarantees that the two broods will never emerge in the same year and compete with each other. Is it far-fetched to think the prime numbers are not a coincidence? No, not at all – many scientists believe that the cycles evolved this way for a reason – read more in this Scientific American article.