236 THE HAUNTS OF LIFE 
gave some hints to the early makers of aero- 
planes, are not only very swift, but have an 
astonishing power of changing their direction 
instantaneously. This is well suited for catch- 
ing other insects on the wing. Another re- 
markable feature in the flight of dragon-flies 
is that when they pass from a sunny to a 
shaded part they often begin at once to prac- 
tise that mysterious kind of flight called 
“soaring,” so well seen in vultures circling in 
mid-air; that is to say, they continue moving, 
but without any visible wing-strokes. 
There is no end to the interesting peculiari- 
ties of flight in different orders of insects. 
Bees and their relatives have microscopic 
hooklets on the front edge of the hind-wings 
which fix on to a bar on the hind edge of the 
fore-wings, so that the two wings on each side 
act as one. In moths and butterflies the same 
result comes about less perfectly. Beetles 
spread out their heavy fore-wings—too heavy 
to be used in striking the air—and clamp 
them at right angles to the length of the body, 
so that they serve as vol-planes when the 
lightly built hind-wings strike the air. In 
two-winged flies the hind-wings are turned 
into rapidly quivering “poisers,” each like a 
