MOTIONS OF INSECTS. 309 



has very short anterior legs, or rather arms ; while the 

 two posterior pair are very long. Its antennae also are 

 long. When it walks, which it does very slowly, with 

 a solemn measured step, its fore legs, which perhaps are 

 useful only in climbing, or to seize its prey, are applied 

 to the body, and the antennae being bent, their extremity, 

 which is rather thick, is made to rest upon the surface 

 on which the animal moves, and so supply the place of 

 fore-legs*. Mr. Curtis suspects that Xyela pusilla, a 

 hymenopterous insect related to Xiphydria, uses its 

 maxillary palpi as legs b . I have observed that mites 

 often use the long hairs with which the tail of some spe- 

 cies is furnished, to assist them in walking. 



Another mode of motion with which many insects are 

 endowed is jumping. This is generally the result of the 

 sudden unbending of the articulations of the posterior 

 legs and other organs, which before had received more 

 than their natural bend. This unbending impresses a 

 violent rotatory motion upon these parts, the impulse of 

 which being communicated to the centre of gravity, 

 causes the animal to spring into the air with a determi- 

 nate velocity, opposed to its weight more or less di- 

 rectly^ Various are the organs by which these crea- 

 tures are enabled to effect this motion. The majority 

 do it by a peculiar conformation of the hind legs; others, 

 by a pectoral process; and others, again, by means of 

 certain elastic appendages to the abdomen. 



The hind legs of many beetles are furnished with 

 remarkably large and thick thighs. Of this descrip- 

 tion are several species of weevils; for instance, Or- 



* De Geer, iii. 324 b Brit. Ent. i. /. xxx./. 4. 



c Cuvier, Anat. Comp. i. 496 



