MOTIONS OF INSECTS. 



249 



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 I have 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 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 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 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. 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 Baccamm), 

 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 



Lesser, 1. i. 248, note 24. 



2 Linn. Trans, xi. 13. 



