Synchronized Emergence | The Sounds of Cicadas Will Soon Fill the Air


April 6, 2021
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In mere weeks, one of the most spectacular natural phenomena will begin to take place in the Eastern part of the US – the synchronized emergence of trillions of periodical cicadas (Magicicada spp.). These unusual insects have spent the past 17 years feeding underground, and once the soil temperature reaches about 64 degrees, they will head for the surface. Once there, they will fill the trees and the sound of their mating songs will fill the air. Their loud rasping call can be up to 80-100 decibels, about as loud as a lawnmower.

For approximately 2-4 weeks, they will court, mate, and lay eggs, setting the stage for the next big emergence, which won’t take place until 2038. This can be quite an inconvenience to residents in the areas in which they emerge, but the sheer numbers of these large insects will provide a once-in-a-lifetime feast for many animals, and the decomposition of their bodies will deliver a huge dose of fertilizer to plants and trees. To Mother Nature, this is a very beneficial occurrence!

The name of this particular brood is Brood X, because it is the tenth brood to be studied by entomologists. There are 15 and Brood X has the greatest range and concentration of them all, so it’s a big deal! Brood X spans 15 states from Georgia to New York and West to the Mississippi river.

Periodical cicadas are a bit different from the cicadas we have here in Texas, which are known as annual cicadas. Their life-cycles range from 1 to 9 years and individuals emerge every year, but they are not synchronized. They are typically green with black and brown markings and green wing veins. Periodical cicadas emerge together either every 13 or 17 years, depending on the species. They are quite striking with black bodies, red eyes, and orange wing veins.

Why do they all emerge together? Scientists believe this is a survival strategy known as predator satiation. The idea is to be present in such great numbers, that even if all the predators fill their bellies with cicadas, there will still be enough present to reproduce and perpetuate the species. Why do they take 17 years? This is one of those great mysteries, but the leading theory is that they are large insects with a diet poor in nutrients, so it takes them a long time to develop. Are these insects harmful? Not at all. They do not bite and they are not toxic at all. In fact, some find them to be quite tasty!

Many confuse these harmless insects with locusts, which are actually the migratory form of grasshoppers. Unlike grasshoppers, which have chewing mouthparts, cicadas have sucking mouthparts and they slowly suck the sap from tree roots underground, causing no real damage to trees. They do not cause damage to crops or garden plants.

My advice to anyone that lives in or plans to visit the East coast in the months of May and June: Enjoy the show! With climate change and other factors at play, we do not know how many more times it will happen.

Erin M
Authored By Erin M Mills

Erin Mills received her undergraduate degree in Entomology from Texas A&M University in 2004, and after a short tour of the pest control industry, joined HMNS as the Cockrell Butterfly Center's Insect Zoo Manager in 2005. Over the years she expanded the butterfly center's live arthropod collection, developed the ever popular "Bugs on Wheels" outreach program, and continued to establish her role as HMNS's insect expert. In October of 2016, she achieved her long time goal of becoming the Director of the Cockrell Butterfly Center and in January of 2021, she joined the team at HMNS Sugar Land as the Director of Nature Programming. Erin leads hikes in Brazos Bend State Park and provides fun, hands-on nature-based experiences at HMNS Sugar Land. As a Board Certified Entomologist, Erin has extensive knowledge of insect identification, ecology, plant relationships, husbandry, really any insect-related topic!

One response to “Synchronized Emergence | The Sounds of Cicadas Will Soon Fill the Air”

  1. Karen Friedman says:

    Hello Erin, i really appreciate all your posts especially an old one about your Katydids! Info on them is very limited so I got so excited about your knowledge and fondness for these magical creatures. I rescued a fork tailed bush Katydid, (I got the honor to take a video of her laying eggs in the epidermis of a leaf)! Her eggs hatched prematurely January 20th when in Oregon they are born in late Spring.
    * I’m thrilled to say most are still alive! I found NO info on premature insect care. Romaine and Kale are always available for the nymphs. Strawberries, Blackberries, apples and Oranges etc are a hit but nothing gets them going like a dead insect and yes…. I’m discovering they love live ones as well. To my surprise one of them came out of hiding and pounced on a live ant and savagely wrestled with it. They also eat larger dead insects. In small groups they eat the insect from the inside and tend not to leave. From food to shelter. I have to be very careful what I throw away.
    My one concern is the degree to which they hide. If the leaf they were born in wasn’t decaying they would all live in there as they did for the first couple months. Some still live inside the leaf and the rest went off in groups. I put in a washed pine cone and some like that. Some live hidden in the small trees I put in for climbing and molting as long as there is a piece of lettuce to hide under. However, now I can’t throw away the twigs to my fake trees because many at a time will live inside them and I’ve had to switch to plastic aquarium trees. The larger nymphs live in groups in the rubber seals of the tank. (Green ones live with green and black ones live with black.) Are katydids racists? I’m sure there are better explanations! They do not look like the fork tailed nymphs yet though some just started to grow the black and white antennas.
    * Cleaning is getting very hard. The only time I see them is when I hand feed them ants. They stick out half their head and patiently wait their turn. My biggest sighting was when the one nymph lunged at the live ant. Could being so premature effect this illusive habit and maybe they’ll get less fearful as they mature? I’m afraid their shyness may effect their molting or just be a negative implication for some other problem.
    * I’d be so greatful for any input, family & friends avoid me and I have even worn out google. Thk u so much, Karen
    Ps. I have many more surprising observations but I’m afraid my post is already to long. I have not been involved with anything I’ve learned so much from.❤️

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