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Cicadas

They are everywhere!  Over the past 6 weeks or so we've been subject to the constant din of cicadas.  There are many different  types of cicadas that emerge in different years in different parts of the country.  The ones we are seeing this year are Magicicada Brood II, and they emerge from May through June all along the eastern United States from Connecticut to Virginia every 17 years.  When the soil temperature reaches 64° F one foot deep, the cicadas are warmed up enough to emerge and become active.  

Cicadas, alternatively spelled as Cicala, or Cicale, are insects in the order Hemiptera, suborder Auchenorrhyncha.  Cicadas are in the superfamily Cicadoidea.  Their eyes are prominent and set wide apart.  Cicadas are often called locusts, although they are unrelated to true locusts, which are related to grasshoppers.  Cicadas are related to leafhoppers and spittlebugs.  

 

 

Cicadas are harmless to humans and do not bite or sting.  They may mistake a person's arm for a tree or plant limb and attempt to feed.  Cicadas have a long proboscis that they insert into plant stems in order to feed on the tree's sap.  Cicadas can cause damage to several cultivated crops, shrubs, and trees, mainly in the form of scarring left on tree branches when the females lay their eggs deep in branches.  So you may see the tips of some tree branches that have recently turned brown.  This would be due to the cicadas; but, unless the tree was already weakened, should not be significant enough to cause serious harm.  

You may have noticed birds regaling on the cicadas - a tasty treat high in protein.  Many peoples around the world regularly eat cicadas.  They are known to have been eaten in Ancient Greece as well as China, Malaysia, Burma, parts of Latin America, and the Congo.  Female cicadas are prized for being meatier.  Not surprisingly, shells of cicadas are used in Chinese Traditional Medicine.   

Interesting facts about the 17 year cicada (taken from http://www.cicadamania.com): 

Eye Color - Most 17 year cicadas have red eyes, but they can also have white, gray, blue, yellow, brown, or multi-colored eyes. 

There are 13 year cicadas too!  Magicicada tredecim, Magicicada neotredecim, Magicicada tredecassini, and Magicicada tredecula.  Broods XIX, XXII and XXIII feature these cicadas.   

They’ll land on you if you’re using a power tool or lawn mower.  Cicadas think the sounds made by power tools and lawn maintenance equipment are made by other cicadas.  They get confused and will land on the people using the equipment.  Pro tip: cut your lawn in the early morning or near dusk when the cicadas are less active.  

Cicadas have five eyes - Cicadas have two, obvious, large, compound eyes, and three ocelli.  Ocelli are three jewel-like eyes situated between the two main, compound eyes.  We believe ocelli are used to detect light and darkness.  Ocelli means little eyes in Latin.  

Animals eat them.  Dogs will gorge themselves until they choke.  Squirrels will eat them like corn on the cob.  Wild turkeys will grow fat and juicy on the cicada feast.  Fish go crazy for them too - you can use them as bait, or use lures that mimic them.  

Cicadas “eat” tree fluids.  Cicadas don’t eat solid foods — instead they use their slender, straw-like mouth parts to drink tree fluids.  

Cicadas pee:  Yes cicadas pee, so wear a hat when walking under trees.  People call it “honey dew” or “cicada rain."  

That cicada sound:  Only male cicadas make the sound they’re famous for.  Males have organs on their abdomen called tymbals.  Muscles pop the tymbals in and out, which creates the sound we hear.  Males make different calls for different reasons, and each species has a unique sound.  Females can make sound too — they flick their wings to respond to males.  

There are billions of them: there are literally billions of 17 year cicadas.  Why? One theory suggests that the large number of cicadas overwhelms predators, so predators are never able to eat them all, and many always survive to mate.  This is a survival strategy called “predator satiation.”  

They damage wimpy trees:  The biggest concern about 17 year cicadas is their potential to damage young trees.  The truth is they will damage limbs on the weakest of trees.  You can try hosing them off with water, placing insect barrier tape around the trunk of the trees, or picking them off like grapes.  Cicadas actually benefit the health of trees by aerating the soil around the roots, and trimming the weak or damaged limbs.  

Stragglers: Periodical cicadas that emerge in years before they are supposed to emerge are called stragglers.  

Seventeen and thirteen are prime numbers.  Scientists speculate that one reason why these cicadas emerge in 17 or 13 year cycles is because those are prime numbers.  The fact that 17 and13 are relatively large* prime numbers makes it difficult for predators to synchronize with them.  (*Relative to the average lifespan of an animal.)  Annual cicadas (cicadas that arrive every year) often have wasps specialized to prey on them; periodical cicadas have no such wasp because no wasp synchs with it.  

They use their color to warm up:  Cicadas need to be warm to sing and fly around, but they’re cold blooded.  Their dark exterior absorbs the heat of the sun, which helps to warm them up. 

 

Seventeen and thirteen year broods co-emerge every 221 years.  Cicada broods usually don’t overlap geographically, and it is very rare when they emerge in the same year.  The next time Brood II (the brood emerging this year) will co-emerge with another brood will be in 2115 when it co-emerges with Brood XIX.   

Sources:  http://www.cicadamania.com and http://magicicada.org 

Elizabeth Heath