INSECT SIPPERS AND GNA WERS. 261 
tropical countries, which are near relations of the 
skip-jack, and have two bright shining spots upon 
their shoulders. We might trace out in the lives 
of many of these beetle families the peculiar shape 
of jaws, legs, antennae, and the peculiar colours of 
their wing-cases which fit them for the work they 
have to do, but such knowledge is the work of a 
lifetime, and at least a few words at the end of this 
chapter must be given to the third group of animals 
which remodel their bodies, namely the two-winged * 
flies and gnats. 
Does it not seem strange that while butterflies 
and beetles, dragonflies and grasshoppers, and even 
bees and wasps, have all two pairs of wings, yet our 
common house-fly and bluebottle, in many other 
ways so like bees, have only one pair ? This, how- 
ever, will not seem quite so strange if you look care- 
fully just behind the wings of the fly, for there you 
will find on each side a little stalk with a knob at the 
end, which the creature uses to balance itself as it flies. 
These two stalks are the remains of the second pair of 
wings, which, for some reason unknown to us, must 
have been a disadvantage to the ancestors of the fly, 
and this is all that remains of them. If you cannot find 
them easily in the fly, where they are concealed under 
some little winglets, you will see them clearly in a 
gnat, or, better still, in a daddy-long-legs, in which 
they are so distinct that you may examine them 
without catching or hurting him, by simply putting a 
tumbler over him where he stands and slipping a 
piece of paper underneath. 
* Diptera (from dis % twice ; pteron, wing). 
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