310 MOTIONS OF INSECTS. a 
beetles, walk as fast as they can. One insect, a kind of 
snake-fly (Raphidia Mantispa, F’.), is said to walk upon 
its knees. The crane-flies (Zipula oleracea, L.) and 
shepherd-spiders, (Phalangium, L.) have legs so dispro- 
portionately 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 ob- 
served 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 
zig-zaes. 
Numerous are the insects that run. Almost all the 
predaceous tribes, the black dors, clocks, or ground- 
beetles (Carabide), and their fellow destroyers the Ci- 
cindelide@,—which last 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 a man, whose steps measured two feet, should run 
at the incredible rate of more than twenty miles ina 
minute! How astonishing then are the powers with 
which these little beings are gifted!—The forest-fly 
(Hippobosca), and its kindred genus Ornithomyia pa- 
tasitic upon birds, are extremely difficult to take, as I 
* Lesser, LZ. i, 248, note 24, 
