92 INSECT MISCELLANIES. 



remarks on inaudible sounds, to which we shall after 

 wards advert. 



In another place, Latreille, in mentioning the sin- 

 gular organs called balancers, or poisers [lialteres), 

 says, they occupy exactly the situation of the spines 

 in bees and wasps, with spiracles in the same manner 

 situated behind them, whence it is evident that the 

 hinder part of the chest, where the balancers are, cor- 

 responds to the part which, in the male cicada and 

 the cricket, contains the organs of sound.* From 

 the form of these balancers, as they have been called, 

 being much like a drum-stick, we might be led to 

 suppose them to be the very instrument employed to 

 produce the sound; but, as they have been viewed in 

 a different light, it may be proper to take notice of it. 

 Derham, accordingly, thinks that both these and the 

 winglets [alulcB) in two-winged flies {Diptera), are 

 for rendering the flight more steady. ' If one of the 

 poisers,' he says, ' or one of the lesser auxiliary 

 wings be cut off, the insect will fly as if one side over- 

 balanced the other, until it falleth on the ground ; so 

 if both be cut off they will fly awkwardly and 'un- 

 steadily, manifesting the defect of some very neces- 

 sary part. The use, no doubt, of these poisers, and 

 secondary lesser wings, is to poise the body, and to 

 obviate all the vacillations thereof in flight, serving to 

 the insect, as the long pole, laden at the ends with 

 lead, does to the rope-dancer. 't Schelver, however, 

 found that any mutilation of either one or all of the 

 winglets, or the poisers, in a crane-fly ( Tipula cro- 

 cata) prevented it from flying at all, and he conjec- 

 tures that the poisers are air-holders, J 



Schelver, however, found that a fly continued to 

 buz when the poisers were cut off, — an experiment he 



* Regne Animal, v, 429, Note, ed. 3 829 



t Physico Theology, ii, 169, Note (i). 



t Wiedemann, Archiv. ii, 210. 



