450 MOTIONS OF INSECTS. 



a kind of snake-fly (Mantispa pagana), is said to walk upon its knees. 

 The crane-flies (Tipula oteracea) and shepherd-spiders (PhaJangium) 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 often observed the 

 little midges (Psychoda Latr.), when walking up glass, moving alternately 

 from right to left and from left to right, as humble-bees fly, so as to describe 

 small zigzags. 



Numerous are the insects that run. Almost all the predaceous tribes, 

 the black dors, clocks, or ground-beetles (Eutrechina), and their fellow 

 destroyers the Cicindelte, and other Eupterina which Linne, with much 

 propriety, has denominated the tigers of the insect world are gifted with 

 uncommon powers of motion, and run with great rapidity. The velocity, 

 in this respect, of ants, is also very great. Mr. Delisle observed a fly so 

 minute as to be almost invisible which ran nearly three inches in a demi- 

 second, and in that space made 540 steps. Consequently it could take a 

 thousand steps during one pulsation of the blood of a man in health. 1 

 Which is as if a man, whose steps measured two feet, should run at the 

 incredible rate of more than twenty miles in a minute ! How astonishing, 

 then, are the powers with which these little beings are gifted ! The forest- 

 fly (Hippobosca), and its kindred genus Ornithyomia parasitic upon birds, 

 are extremely difficult to take, as lliave more than once experienced, from 

 their extreme agility. I lost one from this circumstance two years ago, 

 that I found upon the sea-lark (Charadrius Hiaticula), and which appeared 

 to be nondescript. Another most singular insect, which though apterous 

 is nearly related to these I mean the louse of the bat (Nycteribia Vesper- 

 tilionis), is still more remarkable for its swiftness. Its legs, as appears 

 from the observations of Colonel Montague, are fixed in an unusual posi- 

 tion on the upper side of the trunk. " It transports itself," to use the 

 words of the gentleman just mentioned, " with such celerity from one part 

 of the animal it inhabits to the opposite and most distant, although ob- 

 structed by the extreme thickness of the fur, that it is not readily taken." 

 " When two or three were put into a small phial, their agility appeared 

 inconceivably great ; for as their feet are incapable of fixing upon so smooth 

 a body, their whole exertion was employed in laying hold of each other ; 

 and in this most curious struggle they appeared actually flying in circles : 

 and when the bottle was reclined, they would frequently pass from one 

 end to the other with astonishing velocity, accompanied by the same gyra- 

 tions : if by accident they escaped each other, they very soon became mo- 

 tionless ; and as quickly were the whole put in motion again by the least 

 touch of the bottle or the movement of an individual. 2 Incredibly great 

 also is the rapidity with which a little reddish mite, with two black dots 

 on the anterior part of its back (Gamasus Baccarum), common upon straw- 

 berries, moves along. Such is the velocity with which it runs, that it 

 appears rather to glide or fly than to use its legs. 



When insects walk or run, their legs are not the only members that are 

 put in motion. They will not, or rather cannot, stir a step till their antenna 

 are removed from their station of repose and set in action. When the 

 chafers or petalocerous beetles are about to move, these organs, before 



* Lesser, 1, i. 248. note 24. 2 Linn. Trans, xi. 13. 



