MOTIONS OF INSECTS. 485 



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 tliat run. Almost all the predaceous tribes, 

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

 destroyers the Cicindehe, and other Eapterina — 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 

 derai-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.^ 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 (Hippohosca), and its kindred genus Ornithyomia parasitic 

 upon birds, are extremely difficult to take, as 1 have more than once expe- 

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

 years ago that I found upon the sea-lark (Charadrius Hiaticuh), 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 Vespertilionis) , is still more remarkable for its swiftness. Its 

 legs, as appears from the observations of Colonel Montague, are fixed in 

 an unusual position 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 obstructed 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 appearecT 

 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 gyrations: if by accident they escaped each 

 other, they very soon became motionless ; and as quickly were the whole 

 put in motion again by the least touch of the bottle or the movement of 

 an individual.^ Incredibly great also is the rapidity with which a little 

 reddish mite, with two black dots on the anterior part of its back (^Gamasus 

 Baccaruin), common upon strawberries, 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 an- 

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

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

 concealed, instantly appear, and the laminae which terminate them being 

 separated from each other as widely as possible, they begin their march. 

 They employ their antennae, however, not as feelers to explore surrounding 

 objects, — their palpi being rather used for that purpose, — but, it should 



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



41* 



