Insects and their world 



If the hind-legs are specially adapted, this is most often for the 

 purpose of jumping or swimming. The grasshoppers and crickets 

 exemplify the one, and the water-bugs and water-beetles the other 

 (Figs. 14, 51). 



The appendages of the eighth and ninth segments of the abdomen in 

 female insects combine to form the ovipositor, or egg-laying tube. The 

 structure of the ovipositor is closely adapted to the egg-laying habits of 

 the insect, and has been discussed in some detail in Chapter III. 



Apart from these adaptations that have a direct, mechanical use, many 

 insects have adapted their shape and colour to the needs of defence. The 

 stick-insects and the leaf-insects (Phasmida) and some caterpillars 

 (Fig. 39) are an obvious example. The stick-insects have simply 

 evolved a long and cyhndrical shape for every part of the body, with 

 the result that when they sit motionless among twigs they escape 

 the notice of their enemies. Leaf-insects and leaf-butterflies (Fig. 71) 

 have gone further, and have the legs, abdomen and fore-wings flattened 

 and coloured, like leaves: sometimes the resemblance is uncanny, with 

 dark patches which give the impression of holes in the leaf, spots of 

 fungus, or bird-droppings. 



Adaptations to a particular way of life are common among immature 

 insects, and especially among aquatic nymphs and larvae. We have 



Fig. 70. Head of a male horse-fly. Order Diptera, from above, showing 

 how the huge compound eyes are so big that they meet in the middle 



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