INTRODUCTION. 7 



When I go to work in the garden I turn up numerous earth- 

 worms, nearly all belonging to introduced species unless I start to 

 trench in new ground, when I come on native species. The wood- 

 lice are introduced ; so are the earwigs, which are so common in 

 the north end of Dunedin ; so are all the slugs and snails. The 

 bees and humble-bees are introduced, as are the large drone-flies 

 which visit so many of our flowers in autumn and early winter. 

 .\Varly all the plants in our fields, orchards, and gardens, culti- 

 vated ones and weeds alike, are of foreign origin ; so are the 

 aphides and scale insects which infest them. The flies which infest 

 our houses and carry dirt and disease in all directions are 

 foreigners; so are the borers which destroy our houses and furni- 

 ture ; and so also are bugs, fleas, and lice, which are harboured 

 in dirty surroundings. 



The question might well be asked, Where do the native species 

 come in ? The answer would have to be that wherever man goes 

 certain species of animals and plants follow him, and become esta- 

 blished if the conditions are suitable; while another section he 

 either takes with him for their utility or introduces afterwards 

 for various reasons ; and the native species gradually get pushed 

 out. 



Let us consider these two kinds of introductions. The only 

 mammals in New Zealand which were introduced by man uncon- 

 sciously are rats and mice. These accompany man wherever he 

 goes and settles, and do so very much against his will. All the 

 other forms horses, opossums, wallabies, cattle, sheep, goats, pigs, 

 deer, dogs, cats, hares, rabbits, hedgehogs, and guinea-pigs were 

 introduced of set purposes. All the introduced birds were also 

 brought to this country on purpose. So were the introduced fishes 

 salmon, trout, carp, perch, tench, turbot, &c. So were the frogs. 

 As we get lower down the scale of the animal kingdom we find 

 the self-introduced forms increasing in proportion and number, 

 and those brought in for definite reasons becoming fewer. 



No fewer than twenty-eight species of slugs and snails have 

 been introduced into the country. Of these, one a water-snail 

 (Li/iunata stayjialis) was brought here for the purpose of feeding 

 imported trout; all the rest were imported among some kind of 

 agricultural or horticultural produce. The case of the insects is 

 especially interesting. About 270 species have been introduced. 



