GARDEN PESTS IN NEW ZEALAND 



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 hymeno-pterous parasite (Aphelinm 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 

 strict). 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 JOSE SCALE (Aspidiotus perniciosus). Of all scale insects of 

 major importance, the San Jose (Fig. 7, 5) is outstanding, in that it is 

 one of the insects most destructive to deciduous trees and shrubs, a con- 

 siderable number of which are liable to attack. It is of Chinese origin, 

 and first came into prominence when it became established at San Jose, 

 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. 



The list of plants attacked is a long one, but the following may be 

 mentioned: Acacia, hawthorn, quince, privet, poplar, almond, apricot, 

 cherry, plum, peach, pear, apple, gooseberry, currant, roses, willow, 

 ash, elm. 



The female San Jose scale is circular in outline, having a diameter 

 of about one-twenty-fifth of an inch ; in profile it has the form of a flat 

 cone with a crater-like depression at the apex, in the centre of which 

 lies a minute pimple-like prominence; the immature scales are smaller 

 and whitish in colour, while the male scale is elongate-oval in outline, 

 with the crater-like depression toward one end. The individual scales 

 are greyish and are readily overlooked, but when well established upon 

 a tree they form an incrustation giving a characteristic dull silver-grey 

 appearance to the tree; bark, fruit and leaves are infested. A char- 

 acteristic feature of San Jose scale infection is the discolouration of the 

 plant tissues immediately surrounding each insect, which turn a distinct 

 red or purple, giving at once an indication that this scale is present. 



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