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July 13, 2015

Will the cicadas kill my trees, shrubs or flowers?

Filed under: FAQs,Magicicada,Ovipositing — Dan @ 2:41 pm

The primary focus of this article is 17 and 13 year cicadas (Magicicada). Most other cicadas are nothing to worry about, with some exceptions1.

People ask: “Will the cicadas kill my trees, shrubs or flowers?” The sort answer is “maybe”, particularly if your trees are pathetic weaklings. Here are some ways to defend your trees, other than chemical warfare.

Read on for more information:

First, it is important to mention that cicadas do not cause damage to plants by chewing leaves like other insects do, such as caterpillars. These are not the locusts associated with destroying the entire food supply of nations, nor are they the locusts mentioned in the Bible.

Damage from cicadas occurs during ovipositing, or in some extreme cases, when they feed on the roots of trees4.

Grooves made by a cicada during ovipositing:

The weakest limbs of a tree are often temporarily damaged or killed off, the result of which is called flagging, as the leaves of the branch will turn brown and look like a hanging flag. In many cases, they are doing the trees a favor by pruning their weakest branches.

An image of Flagging caused by cicadas:
Periodical Cicada Flagging 3

Cicadas are technically parasites of the trees, and they need the trees to survive throughout their life cycle, so killing trees is not in the cicadas best interest. If cicadas were tree killers, there would be no trees, and no cicadas left.

Big, Hearty North American Trees:

Deciduous trees, like elm, chestnut, ash, maple, and oak, are the preferred host trees of periodical cicadas. They will flag the branches of these trees, but only young ones are at risk.

Don’t belive me? Read this quote from the paper Periodical Cicada (Magicicada cassini) Oviposition Damage: Visually Impressive yet Dynamically Irrelevant by William M. Hook and Robert D. Holt (Am. Midl. Nat. 147:214-224).

The widespread oviposition damage from periodical cicadas did not have any important effects on successional dynamics of the host plants, suggesting that the trees appeared to compensate sufficiently for physiological damage during the emergence.

Periodical cicadas avoid evergreen trees for egg laying because the sap interferes with their egg nests.

Fruit trees: Farmers expect every branch of their fruit trees to yield fruit. They will not tolerate ovipositing & flagging by cicadas.

Cicada Lawyer
Cicada Laywer

The smaller species of Magicicada, ‘cassini & ‘decula, like ovipositing on trees on the edge of a forest, probably because their offspring will be more likely to find grass roots when they leave their egg nests (cicadas initially feed on grass roots until they are big enough to reach and feed on the larger rootlets of trees). An orchard is all “edge of the a forest” because of the rows between the trees, so it ends up being what the legal system would call an “attractive nuisance” for cicadas, because the farmers are baiting the cicadas by providing the ideal egg laying environment, only to kill them with pesticides.

Another consideration is that many fruiting trees are not native to North America. Apples for instance are from Asia, and are not prepared/evolved for the egg-laying behaviors of cicadas.

Small or Ornamental Trees: Cicadas pose the largest threat to small, weakling, ornamental trees, and young deciduous trees. These trees will have the fewest branches, and will not be able to suffer a heavy loss. These are the trees you can worry about, but there are ways to defend them. It makes sense to avoid planting ornamental, fruit or or other deciduous trees the year before and of a cicada emergence — make it the year you concentrate on pavers and low, ground-covering plants like vines and pachysandra.

Shrubs, Vegetables, & Flowers: Given a choice, cicadas will avoid ovipositing on shrubs and long stem flowers, but if the emergence is particularly heavy, they’ll give it a try, out of desperation.

Small flowers, like marigolds, pansies and zinnia will have the best chance of avoiding cicada egg-laying behavior since their stems are so short and unappealing for egg laying.

Personal experience:

I’ve experienced the full duration of two emergences of Brood II. During neither event did I witness the loss of a small tree, shrub or flowering plant. I saw a dogwood tree withstand two emergences, although it did experience ovipositing on nearly every stem, and it lost multiple branches due to flagging. In 1996, our small ornamental red maple withstood the cicada emergence without memorable issues (that plant was lost to a fungal blight many years later). I cannot remember any damage to scrubs such as boxwoods and forsynthia, or garden flowers. Your personal experience might be different.

And of course: Good Luck!

Some references, if you are interested in this topic

1 Certain cicada species in Australia will damage sugar cane and grape vines, but not in North America.

2 Periodical Cicada (Magicicada cassini) Oviposition Damage: Visually Impressive yet Dynamically Irrelevant by William D. Cook & Robert D. Holt.
American Midland Naturalist, Vol. 147, No. 2. (Apr., 2002), pp. 214-224.

3 Spatial variability in oviposition damage by periodical cicadas in a fragmented landscape by William M. Cook, Robert D. Holt & Jin Yao. Oecologia (2001) 127:51–61.

4 Periodical Cicadas in 1963, Brood 23 by D.W. Hamilton & M.L. Cleveland. 1964. Proc. Indiana Acad. Sci. for 1963, 72; 167-170.

July 12, 2015

Why do Magicicada stay underground for 13 or 17 years?

Filed under: FAQs,Life Cycle,Magicicada,Periodical — Dan @ 8:01 pm

People ask: why do periodical cicadas stay underground for 17 or 13 years?

There are three parts to this puzzle that people are interested in:

  1. How cicadas count the years as they go by.
  2. Why prime numbers? 13 and 17 are prime.
  3. Why is their life cycle so long? They are one of the longest living insects.

Cicadas likely don’t count like people do (“1,2,3,4…”) and you won’t find scratch marks inside the cell (where they live underground) of a Magicicada, marking off the years as they go by. However, there is a kind of counting going on, and a good paper to read on that topic is How 17-year cicadas keep track of time by Richard Karban, Carrie A. Black and Steven A. Weinbaum. (Ecology Letters, (2000) Q : 253-256). By altering the seasonal cycles of trees they were able to make Magicicada emerge early, proving that cicadas “count” seasonal cycles, perhaps by monitoring the flow and quality of xylem sap, and not the passage of real time.

Why prime numbers, and why is the life cycle so long? This topic fascinates people. The general consensus is that the long, prime numbered life-cycle makes it difficult for an above-ground animal predator to evolve to specifically predate them. Read Emergence of Prime Numbers as the Result of Evolutionary Strategy by Paulo R. A. Campos, Viviane M. de Oliveira, Ronaldo Giro, and Douglas S. Galva ̃o (PhysRevLett.93.098107) for more on this topic. An argument against that theory is that a fungus, Massospora cicadina, has evolved to attack periodical cicadas regardless of their life cycle. Of course, a fungus is not an animal. Maths are easy for fungi.

There are also questions about why there are 13 and 17 year life cycles, why a 4 year acceleration of a brood might occur1 and why Magicicada straggle.

1 This is a good place to start: Genetic Evidence For Assortative Mating Between 13-Year Cicadas And Sympatric”17-Year Cicadas With 13-Year Life Cycles” Provides Support For Allochronic Speciation by Chris Simon, et al, Evolution, 54(4), 2000, pp. 1326–1336.

July 5, 2015

How can I prevent cicadas from damaging my plants?

Filed under: FAQs,Magicicada — Dan @ 7:17 pm

How can I prevent cicadas from damaging my plants? Assuming they actually will, there are several solutions.

  1. You can wrap netting, or insect exclusion screens, around small trees or individual tree limbs to keep the cicadas off them. You can get this netting from stores that sell landscaping supplies.
  2. You can spray them off with a hose.
  3. You can manually pick them off with your hand.
  4. You can use insect barrier tape or a sticky solution like “Tanglefoot Pest Barrier”. Not my favorite idea, because it will probably pull their tarsal claws off.
  5. See Green Methods for more ideas.

Here is an example of netting being used to contain cicadas, except in this case the cicadas are being kept next to the tree branch and not away from it:

As you might imagine, if the netting can keep them inside, it will also keep then outside.

We recommend that you don’t bother with pesticides for a number of reasons.

  1. New cicadas will continually fly onto your trees from neighbor’s yards, making pesticides futile.
  2. Your pets could become poisoned from ingesting too many treated cicadas.
  3. Collateral damage — you end up killing other insects like honey bees and butterflies.

What are Broods?

Filed under: FAQs,Magicicada,Periodical — Dan @ 6:29 pm

It is important to note that when we talk about cicada broods, we are talking about the 17 & 13 year periodical Magicicada cicadas. We are not talking about Tibicen or other species.

All Broods

There are 12 groups of Magicicadas with 17 year life cycles, and 3 groups of Magicicadas with 13 year life cycles. Each of these groups emerge in a specific series of years, rarely overlapping (17 & 13 year groups co-emerge every 221 years, for example). Each of these groups emerge in the same geographic area their parents emerged. These groups, each assigned a specific Roman numeral, are called broods.

Gene Kritsky’s book, Periodical Cicadas: The Plague and the Puzzle, documents the history of the recognition and naming of the broods. The first person to document that different groups of periodical cicadas emerged in different years was Nathaniel Potter in 1839. Benjamin D. Walsh and Charles V. Riley devised the system for numbering the different broods in 1868, and then C. L. Marlatt sorted the 17 year broods out from the 13 year broods, giving us the system we have today.

Visit our Broods page which features a grid of the Brood names, their life span, when & where they’ll emerge next and links to maps.

Did Someone Offer a Reward for White or Blue-eyed Cicadas?

Filed under: Eye Color,FAQs,Magicicada,Roy Troutman — Dan @ 7:58 am

Is it true that someone has offered a reward for a white or blue-eyed Magicicada cicadas?

This was false and an urban legend until in 2008 when Roy Troutman began to offer rewards for living blue-eyed cicadas for scientific research. All cicadas were released, unharmed.

Important: Roy is no longer offering the reward as he has obtained the cicadas needed for his research. So, don’t bug him, unless you want to tell him that his photos and video are awesome.

White or Blue-eyed Magicicadas cicadas are extremely rare, so finding them can be difficult. I usually find one per emergence, and that is after looking at thousands of cicadas.

Speaking of Roy and White-eyed cicadas, here is a video Roy took of a White-eyed cicada:

And here’s a white and orange-eyed cicada taken by Roy:

Upclose on Marble eyed 17 year cicada

Are cicadas attracted to the sound of lawnmowers and other machinery?

Filed under: Behavior,FAQs,Magicicada — Dan @ 7:41 am

Cicadas on Man Are cicadas attracted to the sound of lawnmowers and other machinery? Yes! Cicadas, particularly Magicicada periodical cicadas, are attracted to lawnmowers, weed-wackers, leaf blowers, hedge trimmers, power drills, etc. If it is loud and vibrates, cicadas will be attracted to it. Why? Most likely because they think your tool is a particularly impressive periodical cicada chorusing center, so males want to join in with the chorus and females want to mate with the particularly impressive males.

So, next time you’ve got the old angle grinder out, don’t be surprised if a cicada lands on your shoulder.

When is a locust not a locust? When the locust is a cicada.

Filed under: FAQs,Identify,Magicicada — Dan @ 6:26 am

Are Cicadas Locusts? The short answer is NO. However, in the U.S.A. we’ve been calling cicadas “locusts” for hundreds of years.

People have seen referring to cicadas, particularly Periodical cicadas, as both flies and “locusts” since the 1600’s, when colonists first documented them.

Gene Kritsky's The Plague and the Puzzle

Gene Kritsky’s book Periodical Cicadas: The Plague and the Puzzle provides a chronology and historical texts of people referring to cicadas as “locusts”. Consider this quote from Pehr Kalm from 1756:

By the Engishmen here they are called Locusts and by the Swedes living here they have gotten the name Grasshoppers. In Latin they could be called Cicada.

It makes some sense that Englishmen would call cicadas Locusts, and Swedes would call them Grasshoppers, because there was only one species of cicada in both England and Sweden. This cicada, Cicadetta montana montana, call is so high-pitched you need electronic assistance to hear it, so most people were not aware of its existence. So, when Englishmen and women encountered cicadas they likely thought “there are a lot of them, they’re big, I’m afraid they’re going to eat my carrots — these must be LOCUSTS”!

Cicadas are indeed not Locusts, Grasshoppers or Flies.

Take a look that the illustration of a true locust below. You’ll notice the true locusts have HUGE rear legs for hopping, long antennae, and relatively long bodies. True locusts chew the plants they consume, while Magicicadas suck fluids from trees.



17-year cicada:

17-year cicada

For more instances of cicadas being confused with other types of insects, read the article These are not cicada insects!

July 3, 2015

How Long Does a Periodical Cicada Emergence Last?

Filed under: FAQs,Magicicada,Periodical — Dan @ 2:47 pm

People often ask: “how long do cicadas last”, “how long will the cicadas be here”, or “how long do cicadas live above ground”?

People probably ask these questions, sadly, because they are tired of listening to the love songs of these cicadas. Like the saying “it is darkest before the dawn”, however, silence is typically a few weeks away.

The length of a local emergence:

The typical periodical cicada emergence will last between 6 to 8 weeks in a single location, with significant chorusing (singing) lasting about 3 to 4. Cool weather or rain can prolong an emergence.

The research paper Emergence of 13-Yr Periodical Cicadas (Cicadidae: Magicicada): Phenology, Mortality, and Predator Satiation by Kathy S. Williams, Kimberly G. Smith, and Frederick M. Stephen1 contains a wonderful study of the arc of a periodical cicada emergence. The entire emergence event takes place within 8 weeks, from the first emerged cicada to the last dead cicada (see Fig 4 in that document 1). The number of live adults reached its peak within two weeks, and then began to die off in significant numbers two weeks after that, due mostly to natural causes. After that the population of cicadas gradually dwindles due to natural deaths and predation.

Length of the chorusing:

Male cicadas will not begin chorusing at the start of an emergence, for a couple of reasons: 1) the first cicadas to emerge, which are primarily males (Fig 3 in 1), are mostly lost to consumption by predators (Fig 6 in 1), 2) Males can’t sing until their adult bodies are fully sclerotized, and 3) they need a significant number of males present before they will chorus. That said, chorusing typically begins within two weeks 2. Males will continue to chorus until enough cicadas die to no longer sustain the chorus, which is why the chorus lasts less than a month.

Length of the emergence of an entire brood:

An emergence spanning multiple states could last between 8 to 10 weeks from when the first cicadas emerge in the South to when the last cicada dies in the North. For example, Brood XXIII began appearing the second to last week of April in Mississippi, and there were likely some left in southern Illinois up until the last week of June.


1 Kathy S. Williams, Kimberly G. Smith, and Frederick M. Stephen, Emergence of 13-Yr Periodical Cicadas (Cicadidae: Magicicada): Phenology, Mortality, and Predator Satiation, (1993), Ecology, Volume 74, Issue 4 (Jun., 1993), 1143-1152
2 Kathy S. Williams and Chris Simon, The Ecology, Behavior, and Evolution of Periodical Cicadas, (1995), Annu.Rev. Entomol. 40:269-95

June 28, 2015

Do cicadas pee?

Filed under: Chremistica,Cicada Anatomy,FAQs,Magicicada — Dan @ 8:11 am

More than a few people have asked Cicada Mania: “do cicadas pee”? Absolutely, cicadas do pee. There are a couple of reasons why:

  • They pee to eliminate excess fluids taken in while drinking xylem (1).
  • They pee to eliminate non-essential amino acids (2).
  • Underground, they could use excess fluid to help moisten and remold their tunnels & cells (2).
  • They might, in some cases, even use it to keep ants from attacking… (3)

You may have been under a cicada-filled tree on a sunny day and felt a sprinkle or two. Don’t worry, it is just watery tree sap (xylem) passed through a cicada.

A detailed explanation of the experience courtesy of Les Daniels:

I’ve experienced this several times where I was on the receiving end of this artificial rain. When many cicadas congregate on warm days, they feed on the tree fluids and often urinate ‘piss’ while doing so. This bug urine is called ‘honey dew.’ The little buggers have pelted me several times while I was observing a little ‘too’ close. It isn’t uncommon. Lastly, the ‘honey dew’ does not stain, or stink. In fact, it feels like rain drops.

Some cicadas seem to pee more than others, for instance the Chremistica umbrosa of South-East Asia. If you walk under an umbrosa, you will need an umbrella! (The Latin root of both words, umbr means shade). Here is a video of Chremistica umbrosa:


1 Records Of The Cicada, Chremistica Umbrosa (Distant, 1904) In Singapore, With Accounts Of Its Mass Emergence (Homoptera: Cicadidae: Cicadinae), Tzi Ming Leong, Aminurashid and Benjamin P. Y-H. Lee, NATURE IN SINGAPORE 2011 4: 163–175, 15 June 2011

2 The Ecology, Behavior, And Evolution Of Periodical Cicadas, Kathy S. Williams and Chris Simon, Annu.Rev. Entomol. 1995. 40:269-95

3 The documentary The Queen of Trees by Deeble & Stone features a segment about Fig Cicadas, that expel pee, sweet with the phloem sap of the fig tree, which is enjoyed by ants and monkeys, which has the side benefit of keeping those predators and nuisances away.

June 27, 2015

What is Predator Satiation?

Filed under: FAQs,Magicicada,Periodical — Dan @ 9:24 pm

Why are there so many Magicicada periodical cicadas, and what does it have to do with the survival of their species? One of the answers is: Predator Satiation.

A predator is any animal that would eat a periodical cicada, i.e., birds, raccoons, squirrels, dogs, snakes, etc. Satiation, in the case of cicadas, means to supply predators with enough cicadas to eat until they are weary of eating and thus avoid them completely.

Predator satiation works like this:
1) Periodical cicadas emerge in tremendous numbers.
2) Adult cicadas are often timid, even after having scleritized.
3) The first cicadas that emerge are eagerly consumed by predators.
4) The predators are so overwhelmed by the bounty of easily eaten cicadas, that they fill themselves to the point of disgust and exhaustion.
5) This gives the remaining cicadas a chance to escape the predators.

The first periodical cicadas are literally “fodder”, in the battle between predators and periodical cicadas, to use a war/video game analogy.

Look at this periodical cicada: it is thinking “hopefully this creature will eat me, so my siblings will live on!”

Magicicada on my finger by Dan from Cicada Mania on Vimeo.

The research paper Emergence of 13-Yr Periodical Cicadas (Cicadidae: Magicicada): Phenology, Mortality, and Predator Satiation by Kathy S. Williams, Kimberly G. Smith, and Frederick M. Stephen (Ecology, Volume 74, Issue 4 (Jun., 1993), 1143-1152) is worth reading if you are interested in this topic. They found that predation of cicadas peaks during the first few days of the emergence, and doesn’t resume in significant numbers until three weeks later (see figure 6, if you read the paper).

Unfortunately this strategy could be detrimental to periodical cicadas in areas with dwindling populations, where there isn’t enough of them to satiate the predators completely.

This strategy might also be used by other types of periodical cicadas like the Chremistica ribhoi of India, or cicadas that emerge in large numbers like Callogaeana festiva of south-east Asia.

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