LETTER XXll 



MOTIONS OF INSECTS. {Larva and Pupa.) 



Amongst the means of defence to which insects have 

 recourse, I have noticed their motions. These shall be 

 the subject of the present letter. I shall not, however, 

 confine myself to those by which they seek to escape 

 from tlieir enemies ; but take a larger and more com- 

 prehensive survey of them, including not only every spe- 

 cies of locomotion, but also the movements they give to 

 different parts of their body when in a state of repose : 

 and in order to render this survey more complete, I shall 

 add to it some account of the various organs and instru- 

 ments by which they move. 



Whenever you go abroad in summer, wherever you 

 turn your eyes and attention, you will see insects in mo- 

 tion. They are flying or sailing every where in the air; 

 dancing in the sun or in the shade ; creeping slowly, or 

 marching soberly, or running swiftly, or jumping upon 

 the ground; traversing your path in all directions; cours- 

 ing over the surface of the waters, or swimming at every 

 depth beneath ; emerging from a subterranean habita- 

 tion, or going into one ; climbing up the trees, or de- 

 scending from them ; glancing from flower to flower ; 



