APPLE MUSSEL SCALE(_Lepidosaphes ulmi_).--The apple mussel scale is now established throughout the temperate regions of the world. It is commonly met with on apple, but has a long list of host plants, among which are pear, hawthorn, willow, poplar, gooseberry, and currant. The insect (Fig. 7, Nos. 2 and 6) forms incrustations on bark and fruit, and is commonly met with at the stalk end of the apple; the individual scale is chocolate-brown in colour, is shaped like the shell of the salt water mussel--hence the name “mussel scale”--and when full grown measures one-eighth of an inch long. A single female is capable of laying up to 700 eggs, in which stage the winter is passed. The eggs hatch in the spring, and the young insects swarm over the host plant in search of a suitable place to settle. A continuous warm spell of weather in the spring will allow all the eggs to hatch almost at one time, but alternating cold spells will retard development, so that emergences take place over a longer period. After emerging from the egg until maturity, when egg-laying again takes place, a period of three months elapses; the insect is a slow breeder, and produces only one brood a year in colder climates, but is two-brooded in warm districts, such as Auckland. A small hymenopterous parasite (_Aphelinus mytilaspidis_), less than one-twenty-fifth of an inch long, attacks this scale, but does not serve as an efficient control; individual scales that have been killed by the parasite show a small hole through which the adult parasite has emerged. The most effective control is secured by treating infested trees with red oil or lime-sulphur during winter. CABBAGE TREE SCALES(_Leucaspis cordylinidis_ and _Leucaspis stricta_).--Cabbage trees and also New Zealand flax often have the leaves encrusted by the white masses of these two native scales. The adult female of one species (_L. cordylinidis_) measures one-eighth of an inch long, is very narrow and straight as a rule, and white in colour, except for the yellow anterior end (Fig. 7, 4). The other species (_L. stricta_) resembles the former, except that the adult is one-eleventh of an inch long, and has the anterior half blackish. In the case of ornamental cabbage trees and flax, control can be effected by removing all dead and scale-infested leaves, thus allowing access to sunlight. SAN JOSÉ SCALE(_Aspidiotus perniciosus_).--Of all scale insects of major importance, the San José (Fig. 7, 5) is outstanding, in that it is one of the insects most destructive to deciduous trees and shrubs, a considerable number of which are liable to attack. It is of Chinese origin, and first came into prominence when it became established at San José, in California, hence its name. Owing to its small size, it is easily overlooked, except when epidemic, and is readily transported upon plants from one country to another.