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September 26, 2015

What is the root of the word Cicada?

Filed under: FAQs — Dan @ 11:58 pm

The Latin root of the word cicada, is cicada!

Looking back a bit farther, the Sanskrit word for cicada is चिश्चिर, which is pronounced cizcira. Not too big a leap from cizcira to cicada.

There are other similar Sanskrit and Latin words, for instance, 17 in Sanskrit is saptadaz, while 17 in Latin is septendecim. Sapta/septen, daz/decim — you can see the similarities.

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.

30 Things Cicadas Do

Filed under: FAQs,Life Cycle — Dan @ 11:59 am

One of the most frequently asked questions we receive is: “what do cicadas do“? This question is similar to the question “what is the purpose of cicadas” — the answers to both questions help people understand why these fascinating, unusual creatures exist at all.

The simplest reduction of their life cycle is:
1) They hatch from an egg.
2) They burrow underground where they will drink from plant roots for most of their lives.
3) They leave the underground, and become adults.
4) The males make sounds that attract females.
5) Males & females court & mate.
6) Females lay fertilized eggs in the branches of plants, and the cycle continues.
7) They die.

The specifics of a cicada’s life cycle varies from species to species, but here is a more detailed view of what cicadas do:

From egg to 1st instar nymph:
1) Cicada nymphs hatch from eggs.

Cicada egg nests

2) Nymphs feed on plant fluids which they accesses thanks to the egg-nest groove made by their mothers.

3) They leave the groove, and drift to the ground. Their decent to the ground doesn’t hurt them because they weigh so little.

4) Once on the ground, they dig into the soil until they find small rootlets, from which they will feed.

Once Underground:
5) Underground, they will tunnel/dig
6) and establish a cell
7) from where they’ll comfortably feed. Cicadas feed on the xylem sap of plants. With the help of bacteria they transform the water, minerals and amino acids found in tree fluids to the tissues of their own bodies.
8) They pee, in fact they seem to use excess plant fluid to moisten soil to help mold the walls of their cells.
9) Throughout their life underground they will move from root to root… as plant root systems change with the seasons, when roots die off, or perhaps to avoid predators.
10) Underground, a cicada may (depending on the species) go through four instars, molting three times (see an image of the four instars).

Preparing to emerge:
11) Cicadas will build a tunnel to the surface of the ground, in preparation for their emergence.

12) Cicadas often take that a step further an build a chimney/turret above ground. This often happens in shady areas or when the ground is muddy.

Once above ground:

13) They emerge from their tunnels
14) Cicadas run as fast as they can…
15) And find a surface perpendicular to the ground, hold tight, and begin to molt…
16) During the molting process (ecdysis), cicadas perform many acrobatic moves to separate themselves from their nymphal skin, including pulling their old trachea from their bodies.
A Brood XIV Magicicada straggler, emerged 4 years late.
17) Once outside their nymphal skin, they will inflate their wings
18) … and expand various parts of their bodies, like their heads.
19) They will change color.
20) Once their bodies are hard enough (sclerotization counts as a thing they do)…
21) They will either seek shelter, perhaps by crawling up higher along a tree trunk…
22) or if your are a Magicicada, you might stick around in the hopes that a predator will eat you.

Mating and Reproduction:

23a) If you are a Male cicada, you are going to sing… unless you belong to a species that cannot sing, in which case, you’ll move your wings in a way that will produce a sounds.
There are many types of songs: a) distress calls, b) calls to establish territory, c) calls to attract females, d) including choruses of many cicadas, and e) courting calls
23b) Female cicadas, and some male cicadas, move their wings to make sounds, also in an effort to attract and engage a mate.
24) Most cicadas (aside from Magicicada during the early days of their adult lives) will try avoid being eaten by predators.
25) They’ll fly, of course.
26) Cicadas, like Magicicada, will establish chorusing centers, which are places where the male cicadas sing together and females come to meet them.
27) Male and female cicadas will court
28) and mate
29) the female cicada will lay her eggs in grooves (ovipositing) she etches into a suitable plant stem, and we’re back to step 1.

30) The last thing cicadas do, of course, is die, and return the nutrients found in their bodies to the soil, where they will be broken down and absorbed by the plants they fed upon.

Some things cicada do not do:

Here are some things cicadas do not do:

1) They don’t seek shelter during the fall months (i.e. they don’t try to live inside your house), unlike Ladybugs or Stinkbugs.
2) They don’t sting or otherwise pass venom onto people.
3) They don’t chew plant leaves, like caterpillars or grasshoppers.
4) They don’t dump garbage in the ocean.

July 6, 2015

Where do Cicadas Live?

Filed under: FAQs — Dan @ 5:32 pm

Once they become adults, cicadas live on and around plants similar to their host plants, often the very same tree where they were born. Depending on the species of cicada, this could be a tree, or perhaps a grass (sugar cane, which some cicadas use as hosts, are giant grasses).

When they are nymphs, which they are during the first stages or instars of their life, they live underground amongst the root systems of the plants they derive nourishment from. While they are there, they dig tunnels and build cells (their living quarters) where they can feed from the rootlets of plants in comfort.

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