As this work is for the benefit of the gardening public, and an endeavour to diffuse some knowledge of certain natural problems, the language of the scientist--which, unfortunately, tends to guard what is known of these problems from the general reader--has been avoided as much as possible; at times, however, this ideal cannot be adhered to, but in such cases the reader should find no difficulty, and should be prepared to become familiar, with the few terms used. To know the scientific names of animals without being acquainted with the animals themselves is a habit to be avoided, and is just about as instructive as memorising the names of people in a town or telephone directory. But animals must be named; though their popular names are used in the following pages and as such names are very often misleading, the scientific names are given in brackets in order to avoid confusion. In such a work as this, illustrations are of great value, and these are given wherever possible. One drawback to illustrations is that the relative proportions of animals may be lost; for example, a microscopic organism might require magnification by some 4,000 times its natural size and so become equal to that of some of the most conspicuous insects. Even with the best illustrations, however, it is essential that the reader becomes familiar with the animals themselves. This should present no difficulty to the reader, since he will find in his garden all of the animals with which he is concerned--mostly insects and their near relatives. Further, of very great assistance to him, he will find the several excellent public museums throughout the country, as well as the specialists at such research institutions as the Cawthron Institute at Nelson. To keep a work for the general reader in a readable form, the desire of the author to cite the sources from which he derives his information must be suppressed. If this were not done, the text would rapidly become littered with endless references, much to the weariness and confusion of the reader. Therefore, it should be remembered that a work of this kind is a compilation from the publications of many scientists, to which is added what little original information the writer himself might possess. Opportunity must be taken here to express one’s appreciation of the assistance given by Mr. W. C. Davies and Mr. L. J. Dumbleton in the preparation of the photographs and drawings, respectively. CHAPTER I. General Review of the Animal Kingdom. At the outset it is advisable, by reviewing the animal kingdom as a whole, to secure in perspective the relationships of the animals with which the horticulturist has to deal.