432 MOTIONS OF INSECTS. 



parable provision made in the feet of such as walk or hang upon smooth 

 surfaces ; the great strength and spring in the legs of such as leap ; the 

 strong-made feet and talons of such as dig ; and, to name no more, the 

 admirable faculty of such as cannot fly, to convey themselves with speed 

 and safety, by the help of their webs, or some other artifice, to make their 

 bodies lighter than the air." 1 



Since the motions, and instruments of motion, of insects are usually 

 very different in their preparatory states, from what they are in the imago 

 or perfect state, I shall therefore consider them separately, and divide my 

 subject into motions of larvae, motions of pupae, and motions of perfect 

 insects. 



I. Amongst larvae there are two classes of movers ; Apodous larvae, or 

 those that move without legs, and Pedate larvae, or those that move by 

 means of legs. I must here observe, that by the term legs, which I use 

 strictly, I mean only jointed organs, that have free motion, and can walk 

 or step alternately ; not those spurious legs without joints, that have no 

 free motion, and cannot walk or take alternate steps ; such as support the 

 middle and anus of the larvae of most Lepidoptera and saw-flies (Serrifera). 



Apodous larvae seldom have occasion to take long journeys ; and many 

 of them, except when about to assume the pupa, only want to change 

 their place or posture, and to follow their food in the substance, whether 

 animal or vegetable, to which, when included in the egg, the parent insect 

 committed them. Legs, therefore, would be of no great use to them, and 

 to these last a considerable impediment. They are capable of three kinds 

 of motion ; they either walk, or jump, or swim. I use walking in an im- 

 proper sense, for want of a better term equally comprehensive : for some 

 may be said to move by gliding, and others (I mean those that, fixing the 

 head to any point, bring the tail up to it, and so proceed) by stepping. 



The motion of serpents was ascribed by some of the ancients ( who were 

 unable to conceive that it could be effected naturally, unless by the aid of 

 legs, wings, or fins) to a preternatural cause. It was supposed to resemble 

 the " incessus deorum" and procured to these animals, amongst other 

 causes, one of the highest and most honourable ranks in the emblematical 

 class of their false divinities. 2 Had they known Sir Joseph Banks's dis- 

 covery, that some serpents push themselves along by the points of their 

 ribs, which Sir E. Home found to be curiously constructed for this pur- 

 pose, their wonder would have been diminished, and their serpent gods 

 undeified. But though serpents can no longer make good their claim to 

 motion more deorum, some insects may take their places ; for there are 

 numbers of larvae that, having neither legs, nor ribs, nor any other points 

 by which they can push themselves forward on a plane, glide along by the 

 alternate contraction and extension of the segments of their body. Had 

 the ancient Egyptians been aware of this, their catalogue of insect divinities 

 would have been wofully crowded. In this annular motion, the animal 

 alternately supports each segment of the body upon the plane of position, 

 which it is enabled to do by the little bundles of muscles attached to the 

 skin, that take their origin within the body. 3 



1 Physico-Theol Ed. 13. 366. 



2 Encycl. Brit., art. Physiology, 709. 



3 Cuvier, Anat. Comp. i. 430. 



