Who Is Brood X and Why Are They Saying These Terrible Things About Them?

Talk about social distancing. These guys have been doing it for 17 years and literally went underground. Now – not in response to the COVID19 vaccinations or the lifting of some restrictions – they are coming out into the world. Some people seem fearful of their return. After all, there are billions of them. They are primarily in the northeastern United States and they won’t be quiet about returning. They have been around for millions of years. Native Americans knew them.

They are periodical cicadas of the genus Magicicada. They are easy to spot with their bright red eyes and bulky bodies. They emerge every 17 years (some species do it in 13) and for a month they go through fever pitch mating. The males are the noisy ones and will create a shrill, buzzing chorus.

But who is this Brood X that is in the news around here? Brood X (the X is for ten) is one of the largest of the 17-year cicada broods. They are emerging now in parts of 15 Eastern states. Brood X was first reported in 1715 in Philadelphia.

May 2004 Brood X Cicadas
Two Brood X cicadas in 2004 (Photo: Tracy Lee – Flickr)

They look a little creepy and some people freak out about any insects, especially ones that fly near them. But we don’t have much to fear from Brood X. They don’t bite, sting, carry diseases, or eat your plants. They’re not poisonous, so don’t freak out if your dog or cat grabs one. Actually, in other parts of the world people eat them. (I have read that they taste like canned asparagus.)

They are a phenomenon.

The misinformed Pilgrims at Plymouth Colony saw them in 1634 and thought they were the locusts of Biblical plagues. They are considered beneficial. They aerate the ground, provide food for birds and mammals, and after they die they contribute nutrients to the soil.

If you say, “I saw cicadas in my yard last year,” you’re correct, but you didn’t see periodical cicadas. You saw annual cicadas, which appear later in the summer.

13 or 17 years seems like an awfully long time to be in hiding but one theory is that as a natural defense mechanism it’s effective since predators cannot rely on or anticipate them as a food source. Like other species, their enormous numbers ensure that there will be enough survivors from predators to produce the next generation.

After hatching, immature cicadas (nymphs) spend 17 or 13 years underground. They feed on tree roots (probably not causing any serious damage) and will emerge in May and transform into adult cicadas.

The Brood X cicadas that are emerging this month hatched from eggs that were laid in tree branches back in the summer of 2004.

The nymphs crawl down the trees and burrow deep into the ground. and have been there ever since, sucking fluid from tree roots and growing steadily.

When they emerge is based on soil temperature. A few hot days aren’t their signal to emerge. It takes a week or more of warm weather to warm the soil deep down. These cicadas are not fooled, like humans, by a few warm days that get them setting out plants in late April or early May that get zapped by a late frost or even snow.

adult emerges
adult emerges from exoskeleton

The nymphs emerge from the ground and usually head for the nearest tree. That is where they will shed their exoskeletons which you have probably found. I have also found them on fence posts and even on the outside walls of my house.

All that noise is males singing by flexing their drum-like organs on either side of the abdomen (tymbals).  After mating, the females slit tender tree branches and deposit their eggs. If you have young trees you want to protect, don’t use pesticides which will be ineffective. You can loosely wrap the branches with cheesecloth to keep the female from laying her eggs.

The adults die soon after mating. In a few weeks, the new brood will head down the tree and burrow into the soil. We won’t see them until 2038.

cicadasafari.org – has an app to see where cicadas have been spotted near you and you can report ones you see. Be a citizen scientist! Go on safari with kids.
Periodical Cicadas: The Brood X Edition (book)
Cecily Cicada – a book for kids, especially good if they are bug fearful.

My post’s title is an allusion to an obscure 1971 film, Who Is Harry Kellerman and Why Is He Saying Those Terrible Things About Me? which was directed by Ulu Grosbard and stars Dustin Hoffman.

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A lifelong educator on and off the Internet. Random by design and predictably irrational. It's turtles all the way down. Dolce far niente.

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