LETTER XXllI. 



MOTIONS OF INSECTS, ilmago.) 



III. XiiE motions of insects in their perfect or imago 

 state are various, and for various purposes ; and the 

 provision of ortjans by which they 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 reposing — and motions of 

 insects in action ; — and thi;^ last head 1 shall further 

 subdivide 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 {Tipulw, F.). — 

 When at rest upon any wall or ceiling, sometimes stand- 

 ing 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 con- 

 stant and uninterrupted during their repose. Unless 

 it be connected with the respiration of the animal, it is 

 not easy to say what is the ol)ject of it. — Moths, when 

 feeling the stimulus of desire, or under alarm, set their 

 whole body into a tremor^. A living specimen of the 



" Peck in Linn. Tram. \'i. 92. 



