Posted by: Rob Viens | May 19, 2012

Eine kleine Nachtmusik in the Forest

On May 19th Darwin was pleasantly appreciating topical fruit – something that he comments on frequently in letters home.  He writes:

“These days have glided away very pleasantly, but with nothing particular to mark their passage. — What will not habit do? I find my eye wanders idly from the Orange to the Banana & from it to the Cocoa Nut; whilst I take no more notice than if they were laurel or apple trees.” (May 18/19)

He also notes thow different the winter evening are at the equator.  In particular, the difference between the still night air of winter in the northern latitudes, and the loud, vibrant winters of the tropics. He notes:

“It is very amusing to hear people complaining of the extreme cold. —the depth of winter, however, brings not with it its usual & solitary silence. In the evening various species of frogs make an almost musical concert; this, as the night advances, is taken up in a higher key by a multitude of Cicadas & Crickets.” (May 18/19)

So tonight,, the crickets and cicada’s preempt their beetle cousins for:

Orthoptera Mania logo

Not to knock, Mozart, but there is nothing quite like a “little serenade” of night music from insects and frogs!  Interestingly they all produce sounds in slightly different ways.

Cicada (members of the Hemiptera Order of insects – the “true bugs”) have noisemakers built into their abdomen called tymbols.  A set of muscles around the tymbols alternates between tightening and relaxing, which causes the membrane of the tymbol to buckle inward and outward.  Each time it does so, it makes a clicking sound. The cicada alternates the muscles very rapidly so it sounds to our ear like a continuous sound.  If i had to draw an analogy for the cicada noisemaker, I’d have to say it was like a little dog training “clicker” pressed in rapid succession (this one is from Dogtrainng.net – the cicada is from Wikipedia Commons):

Dog training clickercicada

Furthermore, the interior of the cicada’s abdomen is hollowed out, allowing the sound made by the tymbols to resonate and be amplified.  One source even notes that this can create a sound up to 120 decibels.  Yikes – that is the decibel level of a pneumatic drill!

By the way – it is only the male cicada that makes noise.  Both the male and the female have a sort of “ear drum” called a tympana which allows them to hear the sound produced by the male.  (Good thing – because it is basically a mating call!)

Cicada song (from New Zealand)

Crickets (from the order Orthoptera) sing (or “chirp”) by rubbing body parts together (though not legs as pop culture suggests).  This is called stridulation. Running along the bottom of a cricket’s wing are serrations, like the teeth of a comb. To chirp the cricket rubs the smooth top side of one wing over the serrated bottom of the other wing.  This is a lot like one of those New Year’s Eve noisemakers that you spin around to make a grinding sound. Like one of these below (this one is sold by My Wooden Toys – the crickets are from Wikipedia Commons):

Rattling noisemakercricket

Like the cicada, it is only the male crickets that chirp, and both male and females have a tympanic membrane to “hear” the sounds of other crickets. Both species are sensitive to temperature and tend to make more noise when it is hotter.  For some species of cricket, you can even use the rate of chirping to determine the temperature.

Several different species of crickets chirping

Finally, frogs sing by passing air through their larynx (what we would call our voice box). Like the other musicians of the forest, frogs have a way of amplifying the sound.  In the case of frogs, there is a vocal sac in which the sound can resonate.  If you have ever seen a frog inflate its throat, you were probably seeing a vocal sac at work.

Frog Vocal sac in action (from Wikipedia Commons):

Frog vocal sac

And just to keep the analogies alive, I guess we could consider the frog to be the kazoo player in the forest trio.  Or maybe it would be more fair to consider the frog the vocalist, the cricket the “strings”, and the cicada the percussion!

Those of you looking for your very own night music, feel free to meditate to the following YouTube video called “Cricket Sounds” (posted by sbrajdic).  It is not Brazil, but you get the idea:

And here are some cicadas from Illinois (posted by Arlingtoncards).  (Maybe not as good for meditation as those crickets…):

For some frog sounds, be sure to look back a couple of weeks ago to the post – A Chorus of Frogs.

Tomorrow I’ll wrap up Beetle Mania Week! with one more surprise beetle guest. Let’s just say that it compliments the night music quite well. Until then… (RJV)

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  1. […] – For more on Darwin’s encounters with forest musicians, be sure to see Eine kleine Nachtmusik in the Forest. Share this:TwitterFacebookLike this:LikeBe the first to like […]


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