New YorK AGRICULTURAL EXPERIMENT STATION. 241 
They are quite complex but each consists principally of a cor- 
rugated ear-like drum which, controlled by a powerful muscle, 
may be made to vibrate rapidly. Plate XXIII, Fig. 2, is from a 
photograph showing one of the drums greatly enlarged. The 
song is usually produced in unison and is shrillest during the 
heat of the day. The warmer the sun the louder the song 
becomes. The locusts seem to be especially sensitive to sunlight 
and heat, as was well illustrated in the writer’s experience at 
Union Springs, June 14, 1899. The day was windy with heavy 
fleecy clouds which frequently obscured the sun. While the sun 
was shining brightly, along the margin of the wood where the 
locusts were most numerous, they were very active, flying fre- 
quently into the air and making an almost deafening noise. AS 
soon, however, as the sun was obscured by a cloud there was a 
decided lessening of activities and a lull in the song, which 
would almost cease if the sun was hidden very long. It is 
unusual for the cicadas to sing during the night, but instances 
have been recorded where the song has suddenly broken out 
long before daylight, but to last for a few minutes only. The 
song has been analyzed by Dr. ©. V. Riley and others and found 
to consist of three distinct notes. 
Injury caused by the periodical cicada.— Contrary to the belief 
held by many, the adult cicadas eat little or nothing. If any 
nourishment is taken it is by the female only, and it is doubtful 
if she, except in very rare instances, takes food. As previously 
stated the larvee and pupe feed underground on the sap from 
the roots of trees, shrubs and vines, but so little is required for 
their slow growth, that except in occasional instances where 
they are unusually abundant, it is not probable that appreciable 
injury is done. The important injury is caused by the females in 
laying their eggs in the twigs. Frequently the twigs and smaller 
limbs are so weakened by the punctures of the female as to 
break off with the slightest wind. Large trees may withstand 
this injury without serious consequences, but small trees of a 
few years’ growth are often seriously injured. 
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