Brood X is Emerging!

February 15th, 2021

Most of us have kicked 2020 to the curb and are searching for new things to look forward to. Add this to your list for “Must Do Spring 2021” — you won’t be able to do it again for another 13-17 years. Brood X will emerge this spring in 15 states, including Tennessee.

What the heck is Brood X? 

Each labeled brood is a generation of cicadas. The 2021 Tennessee brood will be Brood X. Unlike the green, annual cicadas, periodical cicadas are known for their black bodies and five bold red eyes. They are unique to North America and at 17 years, are the longest lived insect known. Periodical broods each have their own range and are concentrated in the central and eastern regions of the United States, and some areas are home to multiple broods. Their huge, simultaneous emergence every 17 years is one of nature’s great mysteries.  Where have they been for the last 17 years? Underground, since 2004!  They are always there, just underground in a nymph form that we don’t see.

What’s going on underground?

Cicada nymphs remain underground at half a foot to two feet deep, molting through five instars (a phase between two periods of molting in the development of an insect larva), and emerge from the ground in the fifth instar. In order to grow, they suck fluids from the roots of plants. Female periodical cicadas lay their eggs in tree branches so when the ant-like nymphs hatch, they can fall to the ground, suck on some tree roots and dig in for the really long growth period. 

What makes them emerge? 

On just the right spring day, when soil temperatures reach 64 degrees Fahrenheit, after sunset and often after a rain, the nymphs climb their way to the surface and emerge together.

Scientists don’t fully comprehend what triggers the cicadas to emerge — some think the insects have a method of counting the number of times deciduous trees cycle their leaves and emerge after the right number. Some simply agree it takes the nymphs 17 years to mature, but are unsure of the prompt that elicits mass conformed emergence. Dr. Chris Simon, a molecular systematist at the University of Connecticut’s Department of Ecology and Evolutionary Biology has a theory: “The year of cicada emergence is cued by what I and others believe to be an internal molecular clock. The clock is most likely calibrated by environmental cues that signify the passage of a year, such as the trees leafing out, changing the composition of the xylem fluid on which they feed. The molecular clock keeps track of the passage of years.”  

As proof of this theory, in 2007 in Cincinnati there was a warm January, a hard freeze in February and then a normal spring, which caused maple trees to produce two leaf sets that year. Hundreds of cicadas feeding on those tree roots emerged a year early, after the trees produced 17 leaf sets in 16 years.

Dr. Gene Kritsky, an entomologist at Mount St. Joseph University in Cincinnati, Ohio believes soil temperature drives the mass materialization within the appearance year. “During the last emergence in our area, I planted temperature probes in the ground all over campus to track the emergence,” he stated. “The cicadas emerged over a period of two weeks after the soil temperature reached 65 degrees.”

There may be 1.5 million periodical cicadas per acre! Research suggests that their huge numbers allow them to overwhelm predators, so enough of them will live on to breed and perpetuate the brood. Safety in numbers!

Leaving behind visible exit holes, periodical cicadas quickly crawl to any nearby vertical structure, preferably a tree or shrub. They shed their skins as they molt into adults, leaving behind their empty shells. Shortly after molting, their wings unfurl and their yellow-white skin darkens as the exoskeleton completely hardens.

They’ve emerged... what now?

They sing! After 17 years underground, it’s time to find a mate and time is short. Males sing to attract females using their tymbal,which are  two rigid, drum-like membranes on the underside of their abdomen.

Most cicadas love the sun, so rain and cloudy skies will dampen their song. Temperature also affects whether they will sing or not — too cold or too hot and the songs weaken. Some cicadas will sing depending on the number and proximity of other cicadas in their area. Periodical cicadas, when there are enough in a given area, will synchronize their songs and form a chorus, like a group effort to attract females. With millions of cicadas present, the sound can reach 100 decibels — the same sound as standing next to a motorcycle revving its engine!

After answering the male cicada by flicking her wings, the female will mate with a male and lay eggs, using her ovipositor like a saw to cut slits into living twigs and branches and then place her fertilized eggs inside. This may damage young branches, which makes the periodical cicada a potential temporary problem for nurseries and orchards. If you have particular trees you need to protect, you can put nets or bags over trees for the period of time the cicadas are active. 

“While they may cause cosmetic damage to trees when laying their eggs, cicadas actually provide a number of benefits to nature," comments Jim Fredericks, chief entomologist for the National Pest Management Association. These benefits include pruning mature trees, aerating the soil, providing a food source for predators, and once they die, their bodies serve as an important source of nitrogen for growing trees. A single female may mate multiple times and lay upwards of 600 eggs during the three to four week lifetime of adults. Eggs hatch in six to ten weeks. The tiny ant-like nymphs emerge from the egg and fall to the ground, burrowing in to start the 17 year cycle again.

Can cicadas harm people or pets?

In short, no. Cicadas are often mistakenly referred to as locusts. Locusts are members of the grasshopper family, which have chewing mouthparts and may damage crops. Cicadas have sucking mouthparts and do not chew, but feed on the xylem of plants. Periodical cicadas will not bite. They have been known to land on people, but don’t freak out — they won’t cause any harm. They aren’t drawn indoors, so no need to worry about them setting up shop inside your living room. 

An explosion of cicadas provides a bounty of food for wildlife and some humans. They are considered a delicacy in many countries and in parts of the United States. Some claim that cicadas are high in protein, but recent research conducted at the University of Cincinnati’s College of Engineering has determined that cicadas may contain high levels of mercury. National Geographic points out that cicadas are gluten-free, low-carb and low fat, so why not throw a dinner party featuring cicadas during the emergence? There are even cookbooks to help you decide how to serve them. 

Cicadas in adult form are so massive in numbers that even if millions of them are eaten, there are still millions left to breed. However, the nymphs can be in trouble while underground. Sucking on plant roots and living underground makes them highly susceptible to chemicals like insecticides and poisons. This classifies them in a vulnerable class of insects, and as another reason to use natural methods when gardening. 

I’ll be collecting cicadas to feed the opossums, red fox, American crow, American toad, tiger salamander, turtles and some of our raptors at Reflection Riding. It’s a free, natural prey item full of nutrients and a great form of enrichment. 

Join me in celebrating this super cool natural phenomenon this spring. Happening only every 17 years, this is something to marvel at and celebrate. Maybe a local brewery will make a periodical cicada brew!

Posted by Tish Gailmard  | Category: wildlife

Ask a Botanist

February 15th, 2021

Dear Charlie,

Can you help with fruit problems?  I live in Signal Mtn.  I know these questions are out of season but want information for the Spring.

1.) My grapes grow to pea-size then shrivel and die!?  Any suggestions?

2.) My two apple trees get rust spots all over (cedar rust?).  What is the best way to treat and when?  Will any treatment affect the fruit?


J. Taylor Walker

Hi Taylor,

I do have a few suggestions for both of your crops.


The situation you describe with your grapes is not unusual.  It is referred to as mummification and can happen in only a few days.  The causes of this problem are one of possibly four situations;

  1. Excess sunlight: This probably is not the problem now but the conditions for it could have been established many weeks ago.  

  2. Late Season Dehydration: This may have been at least partially responsible for the shriveled grapes. We did have a few weeks of dry weather in the mid-autumn timeframe; however, I doubt that this is your problem, too.

  3. Sugar-Accumulation Disorder: This occurs when the normal fluids, mostly water, are lost from the fruits, and the sugars (usually glucose), are concentrated and increase the osmotic potential of the cells. The result is a shriveling of the grapes.

  4. Bunchstem Necrosis; This is a dying of the stem that supports the grape clusters. Often the first indications of this disease are the spotting on the stem leading to each grape. Of all the causes of the shriveling of your grapes, this one seems to be quite logical.

As far as ideas for solving this problem for the next growing season, I have a few thoughts.  First of all, you might want to water your vineyard more next season, including a regime of water applied to the vines if there has been no rain for the past 5-10 days.  This would help to cure conditions b-d above.  You might take soil samples from around your vines and send them to the Extension Service folks to get an idea of the nutrients that either are or are not in the soil. I assume you are fertilizing the soil about every 4-6 months during the growing season.


I think your identification is correct, Taylor. That bullseye design on the leaf is characteristic. But there are a lot of rusts in our area and this one on your apple tree does not seem to be damaging to the tree, at least not yet.

This group of fungi (family Pucciniaceae) usually require two hosts in order for the life cycle to be complete. The first is some apple or apple relative – which you have. The second is a member of the group that the easter red cedar is in, the junipers.  You could just cut down nearby cedars in your neighborhood and thereby break the cycle. But since the fungal spores can travel long distances (e.g., 300 – 500 yards) on the wind, you’d have to cut down a lot of cedars and some people would not be too happy on Signal Mountain.  

If you see the sores on the apples or on the tree leaves, it is too late to treat them this year.  Wait until the leaves fall and the apple tree becomes dormant for the winter.

  1. Rake up all the leaves under the trees and either burn them or transport them (perhaps with your garbage) away from your property.  You might not want to recycle them because you don’t want to infect some other area, either on your property or elsewhere in your neighborhood. However, after you have raked up the leaves from the last season’s growth, you may find this enough to control the rust. Minor contamination will not harm either the fruit or the trees.

  2. Treat the soil around your trees with copper as either a liquid spray or in a granular form. This can be purchased from one of our big box stores or ordered online. Please follow the directions carefully. In most cases, if one ounce is called for in the directions two ounces is NOT better.

You asked about rust treatments.  As of December 2020, there are no fungicides that can be applied to edible fruit in the United States except by a licensed pesticide applicator. An alternative solution is to remove the infected trees and replace them with rust-resistant individuals.  You won’t get any apples for probably 3 – 5 years.

I hope this helps.


Good morning! 

We have been slowly cleaning out trash from the woods surrounding our house. Unfortunately, the people who renovated many of the homes in the area thirty years ago threw all the materials and trash into the woods instead of using a dumpster. We have managed to pull out most of it but I have a question on rugs. Many of the folded-up rugs that were tossed have become their own little ecosystem — even housing scores of newts and beetles. Some of the rugs have also begun to grow into the tree roots and have beautiful moss growing on them or have become a part of the hill so that less erosion happens. I am inclined to leave them be, despite them technically being trash. May I have a second opinion? 

Thank you for your time!


Tirzah Burns

Hi Tirzah,

Thanks for your comment and question.

My short answer to your thoughts is, first, you should make your decision concerning your yard based on your own feelings. BUT my idea is that, if the rugs don’t bother you, they should be left there to develop their ecosystem and feed whatever other animals, fungi, or plants have come to depend on them. Of course, I assume the rugs are organic rugs (cotton, wool, etc.) and will be decomposed in a few years. Of course, if they were placed there 30+years ago, they probably are nylon, rayon, etc. If they are synthetic, they may last for many more years.

Another issue to consider is whether the ecosystem provided by the rugs are contributing to animals that would do damage to other parts of your property. This would include mice and rats that could eventually invade your home.

These rugs seem to have developed their own ecosystem and now are generating food for many other organisms. By removing the rugs, these ecosystems would have to start over.

In short, I wouldn’t do anything other than an occasional sprucing up the area. But even that may harm the critters that are there. Leave ‘em be!

Thanks for your curiosity.


Posted by Charlie Belin  | Category: native plants

Sugar Maple

February 8th, 2021

Acer Saccharum

Long-lived and relatively slow growing, the sugar maple (Acer saccharum) is a large deciduous tree with a rounded, dense crown. It typically grows to 70-100 feet in natural conditions and can have a diameter of 2-3 feet, although they can grow significantly larger. Being essentially a dioecious species, each tree will produce either male or female flowers, but some individuals can exhibit monecious tendencies, especially on different branches. The flowers of this tree are small, yellow, and inconspicuous, and appear with leaf break in early spring. They produce a winged fruit called a samara. These seeds are commonly known as “helicopter seeds,” as they spiral to the ground in early fall.The sugar maple exhibits an oppositely arranged leaf formation that is palmately lobed with five deep long-pointed lobes which have few narrow long-pointed teeth. The leaves typically have a rich yellow or orange hue in the fall, although there is some variation. The bark is light grey-brown, becoming darker, rough, and deeply furrowed into narrow scaly ridges as the plant matures.


The sugar maple is a cold-hardy species and prevalent in much of the mixed hardwood forest of the eastern U.S. Its range extends south from Canada to the mountains of northern Georgia, and southwest to Missouri. This maple species is considered widespread in its native range but becomes less prevalent and more restricted as you go south into warmer climates. In the northeast part of its range, the tree inhabits elevations up to 2500’, and in its southern ranges, the sugar maple typically occurs at higher elevations of 3000’ - 5500’ which supports the maple’s love for cool, moist environments. 

Acer saccharum typically occurs in cove forests and other rich, mesic forests, especially over areas abundant in magnesium, iron, and lime. This species can also be found in dry forests and upland woods, and less typically will extend into high elevation northern hardwood forests with acidic conditions. The sugar maple is intolerant of pure sand, swampy soils and xeric conditions. Like most other maples, the sugar maple seems to be extremely shade tolerant and prospers in forest complexes where it acts as an understory plant, capitalizing on canopy light-gaps with rapid growth towards the sun.


Acer saccharum makes an excellent specimen tree with its brilliant fall colors and is a perfect shade tree to protect from the summer heat. This tree is intolerant of pollution and salt, making it a poor candidate for use as a street or urban tree where these conditions are a problem. This tree survives in hardiness zones 3-8.

Sugar maple is among the leading woods used for commercial and artisan products due to its hard, strong quality. Its lumber is utilized for high quality flooring, veneer, and boxes as well as items such as gunstocks, musical instruments, and even bowling pins. Occasionally, the trees develop special wood grain patterns because of growing conditions, making this wood even more valuable; one such grain pattern is called “birdseye maple.”

Most iconically, the sugar maple is known for its production of sweet maple syrup. Being the only tree for commercial maple syrup production, this species sustains a multi-billion dollar industry in the United States and Canada. Trees yield 5-60 gallons of tree sap per year, which is then boiled and put under reverse osmosis to make syrup. It takes roughly 32 gallons of sap to create one gallon of syrup. It should be noted that syrup tapping occurs primarily in its northern range, as the warmer temperatures of the south hinder sap flow.

interesting information

Saccharum, the specific epithet, means “sugary,” referring to the tree sap. Saccharum is also the genus name for sugarcane. Native Americans taught european settlers to tap the trees as a food and sugar source. For ages, idigenous peoples used maple syrup, as well as honey, as their staple sweetening agents. They used these to create sugars, candies, fermented beer, and even vinegars. 

The maple leaf is Canada's national symbol, as can be seen on the national flag. Not surprising, seeing that the province of Quebec produces 70% of the world’s maple syrup, and constitutes 90% of Canada’s $360 million maple syrup export!

Works Cited

Caleb Gruber is Reflection Riding's Land Conservation Intern. The purpose of this internships at Reflection Riding is to develop databases and catalogs to assist in both maintaining our campus and helping private landowners develop natural habitats focused on biodiversity from the ground up.

Posted by Bess Turner  | Category: native plants

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