INSECTS 



heads and the protecting flaps beneath, and the sound 

 comes out in perceptibly increased volume. There can 

 be little doubt that the air chamber of the body and the 

 ventral membranes are important accessories in the 

 sound-producing apparatus. Living cicadas are often 

 found with half or more of the abdomen broken off, leav- 

 ing the air sac open to the exterior. Such individuals 

 may vibrate the drumheads, but the sound produced is 

 weak and entirely lacks the quality of that made by the 

 perfect insect. 



Wherever the periodical cicada appears in great num- 

 bers, the daily choruses of the males leave an impression 

 long remembered in the neighborhood; and, curiously, 

 the sound appears to become increasingly louder in 

 retrospect, until, after the lapse of years, each hearer is 

 convinced it was a deafening clamor that almost deprived 

 him of his senses. Fortunately the cicadas are day- 

 time performers and are seldom heard at night. The 

 song of the periodical species has no resemblance to the 

 shrill, undulating screech of the annual cicadas so com- 

 mon every summer in August and September. All the 

 notes of the more common large form of the seventeen- 

 year race are characterized by a burr sound, and at 

 least four different utterances may be distinguished; the 

 quality of three of the notes probably depends on the 

 age of the individual insect, the fourth is an expression 

 of fright or anger. 



The simplest notes to be heard are soft purring sounds, 

 generally made by solitary insects sitting low in the 

 bushes, probably individuals that have but recently 

 emerged from the ground. The next is a longer and 

 louder note, characterized by a rougher burr, lasting about 

 five seconds, and always given a falling inflection at the 

 close. This sound is the one popularly known as the 

 "Pharaoh" song, because of a fancied resemblance to 

 the name if the first syllable is sufficiently prolonged and 

 the second allowed to drop off abruptly at the end. It 



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