GARDEN PESTS IX NEW ZEALAND 



two great life-groups animals and plants the plants are of funda- 

 mental importance; without them no animal could exist, since, of all 

 living things, it is the green plants alone that are able to convert the 

 inorganic chemical constituents in soil, air and water into living matter 

 or protoplasm; and all animals, either directly or indirectly, are 

 dependent upon plants for their food supply. Plants, therefore, may be 

 looked upon as the primary producers of life, and animals as the 

 consumers. It is in this respect that the horticulturist becomes 

 interested, in that certain of these consumers destroy too many of the 

 plants grown by him for other purposes; fortunately, not all of the 

 consumers are destructive; many are of very great use to the horticul- 

 turist and mankind in general. 



The last point is well illustrated by the following classification of 

 the animal kingdom based upon, the part it plays in human welfare; 

 this is a modification of the scheme adopted by the British Museum of 

 Natural History: 



Group I. Wild or domesticated animals used by man as beasts of 

 burden, source of food, or in the manufacture of various products e.g.., 

 sponges, crayfish, bees, silk-worms, shell-fish, and various vertebrates., 

 as fish, birds and mammals. 



Group II. Animals detrimental to man's welfare, attacking man 

 himself; animals and plants of value to him, or the products derived 

 therefrom e.g.., Protozoa, parasitic worms, mites, insects, and such 

 vertebrates as certain birds and mammals. 



Group III. Animals aiding man's welfare, as scavengers, or by 

 pollinating flowers, or by attacking and checkingpmieh animals as are 

 included in Group II. e.g., Protozoa, parasitic worms, earthworms, 

 parasitic insects, spiders, and such vertebrates as certain birds and 

 mammals. 



An analysis of the above classification shows that animals both aid 

 and hinder the progress of man, hence the use of the terms "beneficiaP 

 and "destructive." In nature, however, these terms are not altogether 

 applicable in the same sense, since the balance maintained between 

 animals and plants under natural conditions is an extremely fluctuating 

 one, though sufficient for natural purposes; with man, however, the case 

 is different. In order to compete in the world's markets, and to supply 

 the growing demands of increasing population, a much higher and 

 dependable standard of productivity is required than is found in nature. 

 Consequently, whilst utilising, and increasing the efficiency of the so- 

 called natural enemies as auxiliaries in his fight against destructive 

 animals, man has found it necessary to develop an effective system of 

 artificial control, involving chemicals, resistant plants, cultivation, crop 

 rotation, etc., for the purpose of maintaining a more stringent balance 

 to meet his requirements. 



Historical Review of New Zealand Conditions. 



The animal population of European New Zealand is very different 

 from that of pre-European times, a position brought about naturally 

 enough by the changes resulting from agricultural development as 

 practised in the Old World, and the consequent creation of an environ- 

 ment foreign to the country. 



