118 NEW ZEALAND NATURE-STUDY BOOK 
VI.—INSECTS. 
INTRODUCTION.—Insects belong to the sub-kingdom Arthropoda, 
or animals furnished with jointed appendages, and to that division 
of it which includes those animals breathing by means of tracheze 
or air-tubes. 
The amount of insect-life throughout the world is prodigious— 
it is found in climes ranging from arctic to tropic—in dark caves, 
in brilliant sunshine, in water and on land. New Zealand 
contains a large number of insects, a few of which have been 
introduced. The vast majority, however, are native, having 
reached these shores in various ways a very long time ago. The 
relation of insects to flowers is one of great importance, the 
fertilisation of the majority of flowering plants being brought 
about by their agency. In other ways, also, they serve 
very useful purposes ; the common House Fly, for instance, by 
consuming scraps of organic matter, which might otherwise 
decay and give rise to offensive odours, perhaps to disease; and the 
Bee, by converting the sweet nectar of the flowers into delicious 
honey : ink, cochineal, and sealing wax, too, are obtained from 
insect products. Then, too, they constitute the sole food of 
large numbers of birds, and some part of the food of nearly all. 
On the other hand, there are many insects that do us injury. 
The Codlin Moth, which attacks and destroys fruit, and those 
insects which do so much damage to crops, are familiar examples. 
An insect may be defined as a jointed animal having its body 
divided into three distinct regions——viz:, the head, the thorax, and 
the abdomen. It has, moroever, three pairs of legs, and generally 
two pairs of wings, all of which are attached to the thorax. To 
acquire this structure, the creature passes through several 
changes, termed its metamorphoses. 
STRUCTURE OF TYPICAL INSECT. 
The head shews no distinct divisions, but bears the 
eyes, the antenna, and mouth. 
The chest, or thorax, consists of three main divisions, 
to each of which is attached a single pair of legs; each of 
the lower divisions may carry a pair of wings. 
The abdomen is made up in the typical insect of eleven 
segments, but some of these are often wanting. 
