312 MOTIONS OF INSECTS. 



a right line. These spines then lay hold of the surface, 

 and by their pressure enable the body to spring for- 

 wards, when, being assisted by its wings, it will make 

 astonishing leaps, sometimes as much as five or six feet, 

 which is more than 25f) times its own length ; or as if a 

 man of ordinary stature should be able at once to vault 

 through the air to the distance of a quarter of a mile. 

 Upon glass, where the spines are of no use, the insect 

 cannot leap more than six inches a . The species of an- 

 other genus of the homopterous Hemiptera (Chemes), 

 that jump very nimbly by pushing out their shanks, are 

 perhaps assisted in this motion by a remarkable horn 

 looking towards the anus, which arms their posterior 

 hip. Some bugs that leap well, Acanthia saltatoria, &c. 

 seem to have ,no particular apparatus to assist them, 

 except that their posterior tibiae are very long. Several 

 of the minute ichneumons also jump with great agility, 

 but by what means I am unable to say. There is a 

 tribe of spiders, not spinners, that leap even sideways 

 upon their prey. One of these (Salticus scenicus), when 

 about to do this, elevates itself upon its legs, and lifting 

 its head seems to survey the spot before it jumps. 

 When these insects spy a small gnat or fly upon a wall, 

 they creep very gently towards it with short steps, till 

 they come within a convenient distance, when they 

 spring upon it suddenly like a tiger. Bar tram observed 

 one of these spiders that jumped two feet upon a hum- 

 ble-bee. The most amusing account, however, of the 

 motions of these animals is given by the celebrated 

 Evelyn in his Travels. When at Rome, he often ob- 

 served a spider of this kind hunting the flies which 

 a PeGeer, iii. 1/8. 



