(a) An ichneumon (natural size 1¼ in); (b) a chalcid (natural size 1-25 in); (c) a hoverfly (natural size ⅛ in); (d) hoverfly larva (natural size ¼ in); (e) a tachinid fly (natural size ¼ in); (f) a ladybird beetle (natural size ⅕ in); (g) ladybird larva (natural size ¼ in); (h) lacewing (natural size ¼ in); (i) lacewing larva (natural size ⅕ in).
Based on the nature of their diet, birds fall into three principal groups: (1) those feeding almost solely upon seeds and fruits; (2) insectivorous birds feeding on insects and other animals; and (3) the omnivorous species feeding both on insects and vegetable matter. The seed-feeding birds are a potential menace to the agriculturist, though in New Zealand the native species are fundamental to the well-being of the native forests; the insectivorous birds are obviously beneficial, though they devour both destructive and useful insects; while the omnivorous birds may be either useful or harmful, according to the circumstances. It should be remembered that, no matter what the food of the adult bird may be, most species give their young a diet of insects or other animal matter. When it is realised that the weight of nestling birds increases from one-fifth to one-half each day, requiring at times more than half the weight of the nestling in food, one can better visualise the enormous quantities of insects daily destroyed for this purpose. Consider the common house sparrow, which is usually condemned: an analysis of the nestling diet has shown that it consisted of 40 per cent. grain and 60 per cent. insects and related forms, while that of the adult comprised 75 per cent. grain and 25 per cent. insects, etc.
To summarise the situation, it may be said that, on the whole, enormous numbers of insects are destroyed by birds each year, and, unless allowed to become abnormally abundant, the benefit derived from birds outweighs the damage they may cause.
Hedgehog.
The hedgehog was first introduced by the Canterbury Acclimatisation Society in 1870, and later by other societies and private individuals. The animal is now very abundant in many parts of the Dominion. Though condemned and destroyed by some people, who consider it a menace to eggs, chickens and even vegetables, the hedgehog is really a very useful animal, in that, being a night prowler itself, it destroys numerous nocturnal pests, such as slugs and snails, earwigs, grass caterpillars and cut-worms.
The hedgehog, on the approach of winter, constructs a nest in some suitable place, where it becomes torpid and hibernates. On the advent of spring, it becomes active once more, and during summer produces a litter of four young; a second litter is sometimes produced in the autumn.