484 MOTIONS OF INSECTS. 



have more than six feet move in this way, which is not improbahle, from 

 the difficulty of attending at the same time to the movements of so many 

 members, is not easily ascertained. 



The dog-tick (^Ixodes Riciniis), if when young and active it moves in 

 the same way that it does when swohi to an enormous size with blood, 

 seems to afford an exception to the mode of walking just described. It 

 first uses, says Ray, its two anterior legs as antennae to feel out its way, 

 and then fixing them, brings the next pair beyond them, which being also 

 fixed, it takes a second step with the anterior, and so drags its bloated 

 carcass along.^ Redi observes that when scorpions w^alk they use those 

 remarkable comb-like prosesses at the base of their posterior legs to assist 

 them in their motions, extending them and setting them out from the body, 

 as if they were wings : and his observation is confirmed by Amoreux, who 

 calls them ventral swimmers.- I have often noticed a millepede {Julus 

 terrcstris), frequently found under the bark of trees, and where there is 

 not a free circulation of air, the motions of which are worthy of attention. 

 Observed at a little distance, it seems to glide over the surface, like a ser- 

 pent, without legs ; but a nearer inspection shows how its movement is 

 accomplished. Alternate portions of its numerous legs are extended 

 beyond the line of the body, so as to form an obtuse angle with it; while 

 those in the intervals preserve a vertical direction. So that, as long as it 

 keeps moving, little bunches of the legs are alternately in and out from 

 one end to the other of its long body ; and an amusing sight it is to see 

 the undulating line of motion successively beginning at the head and pass- 

 ing off at the tail. The motion of centipedes (^Scolojjendra) , as well 

 as that of this insect and its congeners, is retrogressive as well as progres- 

 sive. Put your finger to the common one (^Lithobius forjicatus) , and it 

 will immediately retrograde, and with the same facility as if it was going 

 forwards. 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 towards 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 fi'om a captive fly, which, however, it 

 did not eat, it v^alked forwards in the ordinary way."^ 



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 bloody-nose beetle 

 (Timarcha tencbricosa) and the oil-beetle {JSIeJoc 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 (Alondspa pagana), \s said to walk upon 

 its knees. The crane-flies (Tipula olcracea) and shepherd-spiders (Pha- 

 langium) have legs so disproportionately long, that they seem to walk upon 

 stilts ; but when we consider that they have to walk over and amongst 

 grass — the former laying its eggs in meadows — we shall see the reason of 

 this conformation. Insects do not always walk in a right line; for I have 



» Hist. Ins. 10. * Redi, Opnsc. i. 80. Amoreux, 44. ^ (Euvr. ii. 426. 



