NOISES OF INSECTS. 395 



racter; who also, with good reason, supposes it to as- 

 sist these animals in the sounds they produce. Speak- 

 ing of Acrida viridissima common with us he says, 

 " In our male grasshoppers, in that part of the right 

 elytrum which is folded horizontally over the trunk, there 

 is a round plate made of very fine transparent membrane, 

 resembling a little mirror or piece of talc, of the tension 

 of a drum. This membrane is surrounded by a strong 

 and prominent nervure, and is concealed under the fold 

 of the left elytrum, which has also several prominent 

 nervures answering to the margin of the membrane or 

 ocellus. There is," he further remarks, " every reason 

 to believe that the brisk movement with which the grass- 

 hopper rubs these nervures against each other, produces 

 a vibration in the membrane augmenting the sound. 

 The males in question sing continually in the hedges 

 and trees during the months of July and August, especi- 

 ally towards sun-set and part of the night. When any 

 one approaches they immediately cease their song a ." 



The last description of singers that I shall notice 

 amongst the Locustina, and which includes the migra- 

 tory locust, are those that are more commonly denomi- 

 nated grasshoppers. To this genus belong the little 

 chirpers that we hear in every sunny bank, and which 

 make vocal every heath. They begin their song which 

 is a short chirp regularly interrupted, in which it differs 

 from that of the Acrida long before sun-rise. In the 

 heat of the day it is intermitted, and resumed in the 

 evening. This sound is thus produced : Applying its 

 posterior shank to the thigh, the animal rubs it briskly 

 against the elytrum b , doing this alternately with the 



a De Geer, iii. 429. b Ibid. 4/0. 



