LETTER XXIII 



MOTIONS OF INSECTS. {Imago.) 



III. The motions of insects in their perfect or imago 

 state are various, and for various purposes; and the pro- 

 vision of organs by which tliey are enabled to effect 

 them is equally diversified and wonderful. It will be 

 convenient to divide this multifarious subject; I shall 

 therefore consider their motions under two principal 

 heads: — motions of insects rcpositig — and motions of in- 

 sects in action ; — and this last head I- shall further sub- 

 divide into motions whose object is change of place, and 

 sportive motions. 



The first of these, motions of insects reposing, will 

 not detain us long. The most remarkable is that of the 

 long-legged gnats or crane-flies {Tipnicc). — When at 

 rest upon anj^ wall or ceiling, sometimes standing upon 

 four legs, and sometimes upon five, you may observe 

 them elevate and depress their body alternately. This 

 oscillating movement is produced by the weight of their 

 body and the elasticity of their legs, and is constant and 

 uninterrupted during their repose. Unless it be connect- 

 ed with the respiration of the animal, it is not easy to say 

 what is the object of it. Mollis, when feeling the stimu- 

 lus of desire, or under alarm, set their whole body into 



