OLEARIA GALL MIDGE(_Cecidomyia oleariæ_).--In many parts of New Zealand where _Olearia forsteri_ is grown as a hedge, it is very often disfigured by the formation of malformations, or galls. These are caused by a native midge known as the olearia gall midge. The midge itself resembles the pear midge in structure, but is larger, measuring from one-tenth to one-eighth of an inch long; it is conspicuous on account of its black thorax and blood-red abdomen. In early spring the midges appear and lay their conspicuous masses of bright red eggs upon the buds of the developing shoots. The larvæ, on hatching, set up an irritation in the rapidly-developing tissues, causing the latter to swell and become malformed into bunches of rosette-like galls. If the latter are cut open, a number of the yellowish larvæ will be found, each in its own compartment within the fleshy gall. There is only one brood of adults each year. Control can be effected to a great extent by cutting back and burning the badly-infested parts during winter, and by pruning the young growth carrying the eggs in the spring. Spraying with nicotine when the midges are active should also help to protect the plants. CHAPTER VIII. Boring and Underground Insects. CODLIN MOTH(_Cydia pomonella_).--The codlin moth caterpillar burrows in developing apples and pears, and such “wormy” fruit is known to everybody. The moth itself is seldom seen, since it lies concealed until after nightfall, when it becomes active and lays its eggs. The insect (Fig. 12a) measures about three-quarters of an inch long, and is inconspicuously, though beautifully, coloured; the fore wings, which cover the body when closed, are light grey, crossed by fine bands of a darker hue, giving the appearance of watered-silk, while at the extremity of each wing is a large bronze spot; the hind wings, seen only when expanded, are of a light brown colour. The minute flat eggs are laid on the foliage of leaves, on the fruit, or even on young bark; they appear at first as glistening white specks, but, as development advances, a red ring develops, and finally a black spot just prior to the caterpillars hatching. In some places the first larvæ developing in the spring enter the fruit by way of the calyx, but under New Zealand conditions it is more usual for entry to be made by boring through the skin of the apple. Having completed their development in the fruit, the caterpillars bore their way out and spin their cocoons beneath the loose bark of the tree trunks; in these cocoons pupation takes place, and from them the next generation of moths develops.