Tag Archives: cicada

Trillions of cicadas emerge once in 17 years. This is that year

It’s called Brood X: a brood of cicadas in the US that only emerges from the earth once every 17 years. They’ve been in a sort of pseudohibernation, feeding on plant sap, waiting, biding their time — and the time is also here. In spring 2021, the trillions of cicadas will emerge, laying their eggs in trees which will hatch 4 to 6 weeks later in more than a dozen states. Then their offspring will head back underground until 2038.

Image credits: Wiki Commons.

The year of the cicada

Researchers call them Magicicada, and it’s a fitting name as their behavior is eerily mystical. They don’t just come out whenever, and they don’t follow a yearly pattern either. They spend either 13 or 17 years underground, feeding on xylem fluids from the roots of deciduous forest trees in the eastern United States. Then, like clockwork, one huge brood comes out — and they’re only active for a few weeks.

Researchers believe the cicadas are genetically programmed to behave like this, but they’re not entirely sure why. It could be that they come out only in prime years (like 13 or 17) to confuse predators, but the mystery of cicadas’ love affair with this unusual lifestyle is far from solved. But what we do know is that when the cicadas do come out, there’s a lot of them.

From New York to Illinois, trillions of cicadas from Brood X (Brood 10) are bound to emerge. We’re talking densities of 1.5 million per acre, a stunning and menacing swarm… that contrary to popular belief, is completely harmless.

Cicadas are often mistaken for locusts, but they’re anything but locusts. They don’t cause long-lasting damage to trees because they don’t eat leaves or branches, and they cause very limited agricultural damage. After more than 16 years of slowly sucking tree roots, Brood X cicadas come out with their energy levels saturated. Many of them don’t feed at all once they leave the underground.

“There will be some crop damage, especially to orchards, but we don’t expect a disaster,” said IU Bloomington biologist Keith Clay in 2004, the last time Brood X came above ground.

Although the idea of a gigantic swarm of insects emerging from the earth can sound scary, there’s no reason to worry. If anything, it’s an opportunity to witness a spectacular part of nature we don’t often get a chance to see. It doesn’t happen anywhere else, and if you live in the eastern US, you may see it in your own backyard. It’s a fascinating and unique moment of nature.

2004 Brood X swarm in Ohio. Image via Wiki Commons.

“Cicadas don’t bite, and they don’t attack people,” Clay said in 2004. “They are not very active when the sun goes down, so the massive noise we’ll hear in the daytime will subside, allowing people to sleep.”

Brood X (Brood 10), the Great Eastern Brood, is one of 15 broods of periodical cicadas that appear regularly throughout the eastern United States. It is one of the largest if not the largest, and it has the greatest range and concentration of any of the 17-year cicadas.

Emergence holes underneath flagstone

Cicada broods in eastern US have been noted for centuries. Historical accounts cite reports of 15- to 17-year recurrences of enormous numbers of “locusts” — which were actually cicadas. Pehr Kalm, a Swedish naturalist visiting Pennsylvania and New Jersey in 1749 on behalf of his nation’s government, observed one such emergence. He described it in a Swedish academic journal in 1756:

“The general opinion is that these insects appear in these fantastic numbers in every seventeenth year. Meanwhile, except for an occasional one which may appear in the summer, they remain underground. There is considerable evidence that these insects appear every seventeenth year in Pennsylvania.”

Researchers now are also interested in cicadas, and this emergence represents a chance to study them in greater detail.

“Given that Brood X is not going to emerge for another 17 years, this opportunity represents a once-in-a-researcher’s-lifetime opportunity to study the impacts of such an event,” said Michael Bowers, program director in NSF’s division of environmental biology, in 2004. “This is the first study to experimentally determine the impact of cicada emergence, adult movement and their impact on woody plants. Cicadas are a major insect herbivore for which we have only limited information.”

Cicada, the "paper airplane with a circuit board". Image: © AFP Laurent Barthelemy

Military wants to use swarms of disposable “Cicada” drones: dropping flies behind enemy lines

A mini-drone that fits in the palm of your hand could give the military an upper hand on the battlefield by providing key intelligence readings. Hundreds of these small, plastic drones could be dropped off a flight and left to scatter across the battlezone. Though they don’t have any engines, these “Cicada” drones are equipped with sensors that help adjust the gliding pattern, directing the drone towards a dropzone with an accuracy within a couple of feet. These are hard to spot since they easily disguise as a bird from afar and once behind the lines can use their sensors and microphones to spy on enemy positions. These can also prove very useful for civilian missions, most notably for gathering meteorological data.

The name “Cicada” is after a species of insect that lays dormant underground for a couple of years, before it bursts through by the swarms. Once outside the insects quickly reproduce, then drop to the ground dead. Researchers at the Naval Research Laboratory  felt inspired and wondered if they could design and deploy drones that are so tiny and numerous, that’s impossible for the enemy to shoot down every single one them. This is how the military’s Cicada, or Covert Autonomous Disposable Aircraft, was born. It’s the smallest and cheapest of any military drone developed thus far. The prototype cost only a thousand dollars, while a full scaled manufactured model could drop to about 250 USD a piece.

It only contains 10 moving parts and no engine, but it makes no difference since it can make its way by gliding just as well. A built in GPS receiver tells the little drone, which looks more like a paper airplane than a military-grade aircraft, where it needs to land, so it constantly adjusts its wings and rudder to get there. In a test about three years ago in Yuma, Arizona, Cicada drones were released from 57,600 feet (17,500 meters). After dropping and gliding for about 11 miles, the drone landed within 15 feet of its target. This could be refined even further, so later versions might land right atop, with pinpoint accuracy.

“It looks like a bird flying down,” said Daniel Edwards, an aerospace engineer at the Naval Research Laboratory. But, he said, “it’s very difficult to see.”

“They are robotic carrier pigeons. You tell them where to go, and they will go there,” Edwards said.

An airplane or balloon could drop hundreds of Cicadas behind enemy lines. Image: NAVAL RESEARCH LABORATORY

An airplane or balloon could drop hundreds of Cicadas behind enemy lines. Image: NAVAL RESEARCH LABORATORY

It would’ve been nice if the Cicada was also fitted with some cameras, but this would have severely compromised the design and entire scope of the drone. Once you have a camera, you also need a storage medium and hardware that can handle serious bandwidth. But it does have ears, which are often more than enough. For instance, a Cicada dropped behind enemy lines in key points near a road can eavesdrop using its built-in microphone. Based on the noise and ground vibration, you can then learn when, how many, and what kind of vehicles are using the road. Cicada is also equipped with  temperature, air pressure and humidity sensors.

What’s more, the Cicada is extremely robust. In test flights, the engineers flew prototypes through all sorts of obstacles. Sometimes it would get hit pretty hard, but came out in working condition nevertheless.

Edwards said. “You can thrown them out of a Cessna or a C-130,” he said.

“They’ve flown through trees. They’ve hit asphalt runways. They have tumbled in gravel. They’ve had sand in them. They only thing that we found that killed them was desert shrubbery,” he said

According to Edwards, both the Pentagon and intelligence agencies are very interested in the Cicada and closely following the research.


Bacteria Becomes two Different species inside an Insect

photo credit: Cicada / Juan Emilio Cucumides Carreño

photo credit: Cicada / Juan Emilio Cucumides Carreño

Evolution is virtually ubiquitous throughout the entire world – organisms evolve into different species, there’s nothing new and interesting about that. However, researchers found a surprising and unusual example of evolution – a three way symbiosis evolved into a four way symbiosis, when one bacteria became two different species inside an insect. Wait, let’s go through that slowly now.

Cicadas generally eat a simple diet consisting of plant sap. They don’t bite or sting (unless they mistake your arm for a tree and try to feed – they’re cute like that), and are generally about as nice as it gets. Two bacteria living inside cicadas (Hodgkinia and Sulcia) take some of the eaten sap and transform it into essential amino acids. In exchange for that, they get to live comfortably inside the cicada, no problem with the internal defenses or anything. This symbiosis has been going on for 10 million years.

However, while exploring the genome of some cicadas, researchers from the University of Montana, Missoula found genetic material from yet another bacteria: Hodgkinia has evolved into two different species, and the three way party has now gone four way.

Study leader John McCutcheon explains:

“When we looked at the genes, they were clearly closely related to each other,” McCutcheon explains in a university statement. “If there was a broken gene in one version of Hodgkinia, it would be complete and functional on the other and visa-versa. So, the functional genes in each, when working together, seem to operate as one.” They’re only complete when they work as a team.

When this relationship began, the cicada and Hodgkinia would have been able to survive without each other – but as time passed, they found this mutually beneficial situation. However, they developed it so well that they weren’t able to live on their own pretty quickly. Hodgkinia didn’t need all its previous functions, so it started “shedding” some of its genetic material. Currently, only 200 genes remain.

But the bacterium took things even further – it developed in two different ways. It is an accidental, non-adaptive evolution – a result of “slop and chance”, as McCutcheon puts it. It also makes the symbiosis even more complex.

“This is an obligate symbiosis,” McCutcheon adds, “all of the organisms in there need each other.”

However, truth be told, it’s not much of a difference for the cicada. The only change is that it relies on three bacteria instead of two to provide it with the nutrients it needs. It happened by chance, it likely won’t have any major impact – but it’s fascinating nonetheless.

Journal Reference: James T. Van Leuven, Russell C. Meister, Chris Simon, John P. McCutcheonemail. Sympatric Speciation in a Bacterial Endosymbiont Results in Two Genomes with the Functionality of One. DOI: http://dx.doi.org/10.1016/j.cell.2014.07.047

Cicada wing destroys bacteria solely through its physical structure

The veined wing of the clanger cicada kills bacteria is able to destroy bacteria by its structure alone – one of the first structures ever found that can do this.

The clanger cicada is an insects that looks like something between a fly and a locust; its wings are covered with a vast hexagonal array of ‘nanopillars’ – basically blunted spikes with sizes comparable to that of bacteria. What happens is that when a bacteria settles on this surface, its cellular membrane sticks to the surface of the nanopillars and stretches into the crevices between them, where it experiences the most strain. When the stretch is powerful enough, the membrane ruptures.

Lead study author Elena Ivanova of Australia’s Swinburne University of Technology in Hawthorne, Victoria worked with a team of biophysicists to come up with an advanced nanoscale model of how this happens. She explains that the rupture is much like “the stretching of an elastic sheet of some kind, such as a latex glove. If you take hold of a piece of latex in both hands and slowly stretch it, it will become thinner at the center, [and] will begin to tear”.


To test their model, the team irradiated bacteria with microwaves to generate cells that had different levels of membrane rigidity. If the model was correct, then the more rigid bacteria would be less likely to rupture between the nanopillars. The results validated their model, but also showed that not all bacteria are destroyed – only those with soft enough membranes.

Further study of the cicada’s wing is needed before its physical-defence properties can be mimicked in man-made materials, but doctors are already rubbing their hands, because if this can be replicated, it could be very useful (say) in hospitals and rooms which you want to keep as bacteria-free as possible.

“This would provide a passive bacteria-killing surface,” she says, adding that it “does not require active agents like detergents, which are often environmentally harmful”.