io INSECTS. 



to learn wisdom, since many of the problems of modern civilisation, involved in 

 the questions concerned in the regulation of increase of population, the proper 

 division of labour, and the support of useless individuals, have been satisfactorily 

 solved by many of the species of insects that live habitually in communities. 



Speaking in a general way, insects may be said to be terrestrial animals, since 

 all the species are fitted more or less completely for atmospheric respiration and for 

 progression on the land ; many of them in addition are furnished with wings, which 

 propel them through the air with amazing velocity. In many of the orders, how- 

 ever, as, for instance, in the beetles and bugs, there are species that have adopted 

 an aquatic mode of life and spend their days in fresh- water ponds and streams in 

 various quarters of the globe. Others again, like some of the gnats and dragon- 

 flies, live in fresh- water during the larval stages of their existence, but quit it on 

 attaining maturity. Insects, too, are sometimes feund on the coast beneath stones 

 and seaweed at low water, but there is only one species of insect that can strictly 

 be called marine ; this is a bug (Halobates) sometimes met with in numbers on 

 the surface of the ocean thousands of miles from land. 



The phenomena known as mimicry and protective resemblance 

 are strikingly exemplified in insect life. The term mimicry is usually 

 applied to cases where a species, otherwise unprotected, lives unmolested owing to 

 its resemblance to another which is gifted with defensive weapons in the form of 

 poison-glands, or with a nauseating flavour that renders it distasteful. Such species 

 as these are usually rendered conspicuous by contrasting patches of bright colour. 

 It is noticeable, for instance, that the patterns of bees and wasps are strikingly 

 diversified, in order that the insects may be readily recognised and not slain by 

 mistake for other species. Bees and wasps, then, being species that enjoy 

 immunity from attack, are often imitated or mimicked by perfectly harmless flies 

 and moths, and some beetles and animals allied to crickets similarly mimic ants. 

 But the phenomenon of protective resemblance or the mimicry of inanimate 

 objects by which a species is rendered practically invisible amongst its surround- 

 ings on account of its resemblance to a leaf, stone, twig, or bird-dropping, is of far 

 commoner occurrence. On the accompanying Plate a few instances of this kind 

 of adaptation to surroundings are portrayed. Figs. 12, 13, and 18 are the 

 larvae or caterpillars of different species of Lepidoptera, the first two in colour and 

 shape simulating branches, and the last a snail-shell; Figs. 1, 2, 9 and 14 are 

 leaf -like pupae or chrysalids of other kinds of Lepidoptera; while Figs. 3, 5, 7, 11, 

 15, 23, and 24 are the adult stages of members of the same order under different 

 disguises. The most noticeable of these is Fig. 11, representing a large and 

 handsome butterfly, which, when at rest with its wings folded back, exactly 

 resembles a dead leaf, even to the midrib and stem ; while Figs. 23 and 24, exhibit 

 two small moths, which might be readily mistaken for bird-dung. In the 

 Orthoptera, as the insects allied to the cockroaches and grasshoppers are called, 

 the phenomenon is carried to an extent elsewhere unsurpassed in the animal 

 kingdom. This is well shown in the case of the leaf -insect (Fig. 4), the stick- 

 insect (Fig. 8), and the leaf -like locust (Fig. 10). Most of the other figures on 

 the Plate are of less importance. Attention, however, may be drawn to the water- 

 bug (Fig. 16), the young dragon-fly (Fig. 6), the beetle (Fig. 19), the curious bugs 



