MOTIONS OF INSECTS, 305 



sight it is to see the undulating line of motion succes- 

 sively beginning at the head and passing off at the tail. 

 The motion of centipedes (Scolopendra), as well as 

 that of this insect and its congeners, is retrogressive as 

 well as progressive. Put your finger to the common 

 one (Lithobius forficatus\ and it will immediately retro- 

 grade, and with the same facility as if it was going for- 

 wards. This difference, however, is then observable 

 it uses its four hind legs, which, when it moves in the 

 usual way, are dragged after it. Almost all the other 

 apterous insects, as well as many of those in the other 

 orders, can move in all directions ; backwards, and to- 

 wards both sides, as well as forwards. Bonnet mentions 

 a spider (not a spinner) that always walked backwards 

 when it attacked a large insect of its own tribe ; but 

 when it had succeeded in driving it from a captive fly, 

 which however it did not eat, it walked forwards in the 

 ordinary way a . 



Insects vary much in their walking paces : some 

 crawling along ; others walking slowly ; and others 

 moving with a very quick step. The field cricket 

 (Gryllus campestris) creeps very slowly the blbody- 

 nose beetle (Timarcha tenebricosa) and the oil-beetle 

 (Meloe Proscarabceus) march very leisurely; the spider- 

 wasps (Pompilus] walk by starts, as it were, vibrating 

 their wings, at the same time, without expanding them ; 

 while flies, ichneumons, wasps, &c., and many beetles, 

 walk as fast as they can. One insect, a kind of snake- 

 fly (Mantispa pagana), is said to walk upon its knees. 

 The crane-flies (Tipula oleracea) and shepherd-spiders 

 (Phalangium) have legs so disproportionately long, that 



a CEuvr. ii. 426. 

 VOL. II. x 



