GARDEN PESTS IN NEW ZEALAND 



winter is passed in the egg stage, but under glass or in mild climates 

 activity among the different stages- occurs throughout -the year. 



Apart from apple and pear, these insects have been recorded from 

 many plants : Baker's mealy bug (maritimm) on lemon, orange, walnut, 

 willow, elder, ivy, iris; and Comstock's mealy bug on citrus, elder, 

 euonymus, gooseberry, grape, horse chestnut, hydrangea, mulberry, 

 peach, persimmon, plum, poplar, wistaria. 



THE GUM SCALE (Eriococcus coriaceus). This is one of the most 

 spectacularly destructive scale insects now established in the Dominion, 

 It is a native of Australia, and its normal hosts are the several species 

 of eucalyptus, though it is sometimes found on apricot and willow. A 

 characteristic feature of infected eucalyptus is their blackened appear- 

 ance, due to sooty mould growing on the copious honey-dew secreted 

 by the scale. 



On an infested twig or branch, the insects may be so closely packed 

 as to conceal the bark (Fig. 6, d) ; each female lies in a pear-shaped sac 

 of felted secretion, reddish-brown, tawny, or sometimes white in colour, 

 measuring about three-twenty-fifths of an inch long, and having a 

 circular aperture at one end. The enclosed insect is somewhat flattened, 

 oval, and blood-red in colour; when crushed, it leaves a reddish and 

 sticky smear. The developing males are to be found forming white 

 patches of innumerable individuals on the tree trunks under the loose 

 bark (Fig. 6, d). 



The female is viviparous; during spring, mid-summer and autumn 

 immense numbers of young are produced, which, escape through the 

 opening at one end of the female sac, and are carried long distances by 

 the wind. These young insects first settle on the eucalypt leaves, 

 whence they migrate, the females to take up their final position on the 

 twigs and smaller branches, and the males to continue their development 

 on the trunk of the tree. 



The gum tree scale occurs throughout the districts east of the 

 Southern Alps and in the vicinity of Xelson, in the South Island, and 

 over the southern half of the Xorth. Island; it is, however, spreading 

 rapidly northward. 



This pest is held in control by means of the black-ladybird beetle 

 (Rhizobius ventmlis) Fig. 6, d which was imported for the purpose 

 from Australia; birds such as the tui, wax-eye, fantail, blackbird and 

 thrush congregate on infested trees and eat the insect. 



OLIVE SCALE (Saissetia olece). - This insect has a world- wide 

 distribution, and is one of the most important pests of citrus in New 

 Zealand, although it occurs on a wide range of plants; in all cases it 

 infests the fruit, bark, and the under side of leaves. The host plants 

 include citrus, apple, pear, apricot, plum, almond, fig, grape-vine, 

 wistaria, pepper tree, oleander, holly, laurel, palms, camellia, rose. 



The injury caused by the insect is not so much on account of its 

 weakening influence upon the infested plants as of the fact that it 

 copiously secretes honey-dew, so that black mould develops to* a marked 

 degree, necessitating the washing of herbaceous plants and fruit. 



The adult female (Fig. 6c) is hemispherical, and measures about 

 one-fifth of an inch in diameter, a characteristic distinguishing feature 



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