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another, showing all the various modifications of the mouth. So 

 I now draw the head of a cabbage butterfly sideways. In this 

 case the upper lip and the upper jaws have almost disappeared, 

 though their rudiments can be seen, but the two lower jaws are 

 enormously developed — they are joined together but capable of 

 being separated — and forming a tube through which the insect 

 sucks up its food ; when not in use it is curled up like a watch 

 spring, and guarded by the two labial palpi, which stand up on 

 each side of it. 



In the Heteroptera the upper and the lower jaws have become 

 very long and slender like stiff pointed bristles, and these are 

 enclosed in the lower lip, which is greatly prolonged, and which 

 curls up round them forming a sheath — the feelers have almost 

 disappeared. 



This combination of jaws and lip forms the instrument by 

 which they are able to pierce plants and suck their juices, for as 

 a general rule they are vegetarians, though some few are blood- 

 suckers, and some feed on weaker insects. A wound is made by 

 the four internal bristles, and the juice is then drawn up by a 

 gradual contraction and dilatation of the tube formed by the 

 lower lip. This form of mouth was called by Kirby and Spence ' 

 promuscis, from musca, a fly, but it is now generally termed 

 rostrum. This rostrum is either three or four jointed, and when 

 not in use, lies close to the breast between the bases of the legs. 



It is from the formation of their wings that they have received 

 the name " Heteroptera " (diff'erent wings), the upper wings being 

 partly leathery and partly membranous, and the under wings 

 being entirely membranous. 



All insects were thought to pass through four distinct stages or 

 metamorphoses, the egg, the larva, the pupa, and the imago or 

 perfect insect. But with some it appears that this is hardly the 

 case, the Heteroptera for example. When first hatched from the 

 egg, the young larva is very similar to the perfect insect, only it 

 has no trace of wings which come gradually after a series of 



