LOCUSTS AND GRASSHOPPERS (ACRIDHDjE). 91 



The musical knobs of Acridiidse would seem to be 

 modified hairs, and Graber mentions the finding in 

 females of the stages intermediate between knob and 

 hair. Much variety exists in the structure of these 

 instruments in different species ; in Stenobothrus lineatus 

 raised folds replace the musical pegs. 



Some grasshoppers stridulate during flight, by the 

 friction of the wings and wing-covers. Whether this 

 has any real importance remains almost unconsidered. 

 It appears to be under the control of the insects, for 

 they often omit it when alarmed. Some species produce 

 a uniform noise during the whole of their undeviating 

 flight ; others make it only during the intervals of their 

 course, and seem to stridulate more at will. 



Acridian Ears. 



If the body of an Acridian insect be carefully examined, 

 there will be found in the majority of the species, on 

 each side of the first abdominal segment, an organ which 

 there is much reason for believing to be of the nature of 

 an ear. It is situated a little over the articulation of the 

 hind leg, close to the spot where the sound is, as above 

 described, produced, and just behind the first abdominal 

 spiracle. These ears vary in form, but consist of a 

 stretched or tense membrane. The membrane may be 



