450 MOTIONS OF INSECTS. 
a kind of snake-fly (Mantispa pagana), is said to walk upon its knees, 
The crane-flies (Z'ipula oleracea) and shepherd-spiders (Phalangium) 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 ina 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 (Hutrechina), and their fellow 
destroyers the Cicindele, and other Eupterina— which Linné, 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,! 
Which is as if aman, 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. Ilost one from this circumstance two years ago, 
that I found upon the sea-lark (Charadrius Hiaticula), and which appeared 
to be nondescript. Another mest singular insect, which though apterous 
is nearly related to these —I mean the louse of the bat (Wyeteribia Vesper- 
tilionis), is still more remarkable for its swiftness. Its legs, as appears 
from thé 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.? 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. 
hen 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 antenne 
are removed from their station of repose and set in action, When the 
chafers or petalocerous beetles are about to moye, these organs, before 
1 Leaser, 1. i, 248, note 24. 2 Linn, Trans. xi, 13. 
