It’s been about six weeks since the emergence of Brood VIII in Pennsylvania, Ohio, West Virginia and Oklahoma. Now (first week of August) is a good a time as any to check for periodical cicada nymphs that have hatched from eggs laid in branches. Once they hatch they’ll find their way to the ground, where they’ll find and begin feeding on roots for the next 17 years.
Look on branches where cicada laid their eggs.
An illustraition of egg nests:
A nymph on a branch with adult male finger for comparison:
Sometimes the best cicada locations are just a short distance from your home. This summer I came across a grove of pine trees that had two species of Neotibicen: Neotibicen linnei (Linne’s Cicada) and Neotibicen canicularis (Dog-Day Cicada). Neotibicen linnei and Neotibicen canicularis look very similar when they’re adults (appearances vary by location), so it helpful to compare the two species.
This image compares Neotibicen linnei and canicularis when they’ve recently molted (teneral). Note that the N. linnei is yellow and green, while the N. canicularis is a pink/salmon color.
This image compares these cicadas approximately 24 hours after molting. Note that they’ve achieved their adult coloring, which is very similar, but you can see vestiges of the pink on the N. canicularis.
This last image compares the wing shape of N. linnei (foreground) and N. canicularis (background). Both cicadas are standing on the same piece of white paper. The wings of the N. linnei have a sharper bend — see how the tip of the wing is lifted far off the surface of the paper, while the wing of the N. canicularis almost sits on the paper. Also note that the N. linnei is a more vibrant green, and the N. canicularis is more of a drab/olive green.
Read this journal article, to learn how closely these cicadas are related genetically:
HILL, KATHY B. R., DAVID C. MARSHALL, MAXWELL S. MOULDS, & CHRIS SIMON. “Molecular phylogenetics, diversification, and systematics of Tibicen Latreille 1825 and allied cicadas of the tribe Cryptotympanini, with three new genera and emphasis on species from the USA and Canada (Hemiptera: Auchenorrhyncha: Cicadidae).” Zootaxa [Online], 3985.2 (2015): 219–251. Web. 20 Sep. 2017
You might notice that some cicadas have shriveled-up or otherwise damaged wings. Most of the time, wings become damaged during the molting process (ecdysis), specifically while their wings harden (sclerotize). Their wings and body are most vulnerable when they are still soft.
Some reasons why a cicadas’s wings might not get the chance to inflate and harden:
If a cicada molts and its wings are not able to hang downward they won’t inflate with fluids and form properly.
Cicadas often trample each other in the rush to find a place on a tree to molt.
Harsh weather, like wind and rain, knock them to the ground or bend their wings when they’re soft.
Malnutrition.
Physical weakness or defects.
Fungi infection.
Predator attacks.
Just 10 Magicicada (American periodical cicadas) generations ago, the U.S. was mostly forest. Back then it was easy to find a vertical surface to molt on, or a plant stem to hang from. Today most forests have been replaced with agriculture, buildings, lawns, roads, sidewalks, parking lots, etcetera — so it has become increasingly difficult for periodical cicadas to find a good place to hang.
Magicicada can afford to lose a large number of their population due to wing malformations and other critical defects because there are simply so many of them — this loss falls in line with their predator satiation strategy.
However, if Magicicada cicadas lose too much habitat, they will go extinct (brood XI went extinct about 60 years ago). Lawns, roads, sidewalks, and other features of our human habitat create surfaces that are insalubrious for cicada molting.
In the video below, you will see a cicada molting. Note that its wings are able to hang downward and inflate to form properly shaped wings. If the cicada tried to molt on a vertical surface, the odds are its wings would be crumpled.
In the image below, there is a Neotibicen tibicen (not a periodical cicada) that sclerotized (hardened) before completely shedding its nymphal skin.
Although adorable, this Neotibicen will never sing or fly.
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.
2) Nymphs feed on plant fluids which they access thanks to the egg-nest groove made by their mothers.
3) They leave the groove, and drift to the ground. Their descent 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 bacteriathey 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.
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 to 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.
