MOTIONS OF INSECTS. 483 



remarkable, like certain moths, for their long antennae. It was perched 

 upon a blade of grass, and kept moving these organs, which were twice as 

 long as itself, in all directions, as if by means of them it was exploring 

 every thing that occurred in its vicinity. Many Ti pulse, and likewise some 

 mites (^Acarus vibraiis and Gamasus mofa(orius), distinguished by long 

 anterior legs, from this circumstance denominated pedes motatorii by Linne, 

 holding them up in the air impart to them a vibratory motion, resembling 

 that of the antennae of some insects.^ I scarcely need mention, what must 

 often have attracted your attention, the actions of flies when they clean 

 themselves; how busily they rub and wipe the head and thorax with their 

 fore legs, and their wings and abdomen with their hind ones. Perhaps 

 you are not equally aware of the use to which the rove-beetles (^Staphyli- 

 nus L.) put their long abdomen. They turn it over their back not only 

 to put themselves in a threatening attitude, as I lately related, but also to 

 fold up their wings with it, and pack them under their short elytra. 



With respect to the motions of insects in action, they may be subdivided, 

 as was just observed, into motions whose object is change of place — and 

 sportive motions. 



The locomotions of these animals are walking, running, jumping, climb- 

 ing, flying, swimming, and burrowing. I begin with the walkers. 



The mode of their walking depends upon the number and kind of their 

 legs. With regard to these, insects may be divided into four classes ; viz. 

 Hexapods, or those that have only six legs: such are those of every order 

 except the Aptera of Linne, of which only three or four genera belong to 

 this class : — Octopods, or those that have eight legs, including the tribes' 

 of mites (Acarina) ; spiders (^Araneida) ; long-legged spiders (Phalan- 

 giidce) ; and scorpions (^Scorpionidce) : — Polijpods, or those that have 

 fourteen legs, consisting of the wood-lice tribe (^Oniscida) ; — and Myria- 

 pods, or those that have more than fourteen legs — often more than a hun- 

 dred — composed of the two tribes of centipedes (^Scolopendrida) and 

 millepedes (Julidce). The first of these classes may be denominated 

 proper, and the rest improijer insects. The legs of all seem to consist of 

 the same general parts; the hip, trochanter, thigh, shank, and foot ; the 

 four first being usually without joints (though in the Araneida, Stc. the 

 shank has two), and the foot having from one to above forty .^ 



In ivalking and running, the hexapods, like the larva? that have perfect 

 legs, move the anterior and posterior leg of one side and the intermediate 

 of the other alternately, as I have often witnessed. De Ge^er, however, 

 .affirms that they advance each pair of legs at the same time^; but this is 

 contrary to fact, and indeed would make their ordinary motions, instead of 

 walking and running, a kind of canter and gallop. Whether those that 



> De Geer, vi. 335. 



* The most common number of joints in the tarsus is from two to five ; but the Phalan- 

 gidae have sometimes more than forty. In these, under a lens, this part looks like a jointed 

 antenna, 



GeoffVoy, and after him most modern entomologists, has taken the primnnj divisions of 

 the CdhniUern. order from the number of joints in the tarsus ; but this, although perhaps in 

 the majority of cases it may afford a natural division, will not universally. For — not to 

 mention the instance of Pxelnphus, clearly belonpjinjr to the Brarlujptera — both O.aj/eh/s Grav., 

 and another genus that I have separated from it {CarpnUmus K. Ms.), have only two joints 

 in their tarsi. In this tribe, therefore, it can only be used for secondary divisions. — K. 



» De Geer, iii. 284. 



