GARDEN PESTS IN -NEW ZEALAND 



being the three ridges forming the letter H on its upper surface (Fig. 5). 

 According to age, the colour varies from brownish or greyish to jel 

 black, the insect being conspicuous against the lighter background ot! 

 bark or leaf; the small, immature individuals are light brown or 

 yellowish, and almost flat. 



In New Zealand the winter is passed in both egg and larval stages. 

 though a few adults may be found at that time ; on turning over what 

 appears to be an adult, it will usually be found that the female has died 

 and her place taken by numerous eggs (Fig. 5). The average number 

 of eggs produced has been estimated at from 1,500 to 2,000 per female ; 

 at first the eggs are white, but prior to hatching they turn a, deep orange- 

 red. Development is slow, the adult state being reached about three 

 months after time of hatching; egg laying commences about five weeks 

 after maturity, and continues for a period of about six weeks. There is 

 only one generation each year, and all stages may be met with on the 

 one plant; the greatest activity occurs during the summer months. An 

 important natural enemy of this scale is the steel-blue ladybird beetle 

 (Orcus chalybcem), introduced from Australia. 



HEMISPHERICAL SCALE (Sa/issetia hemispherica) . This w r orld-wide 

 species is commonly met with in New Zealand, and, though not a serious 

 pest, has a wide range of host plants, both in the open and under glas- : 

 some of the commoner hosts are citrus, fig, oleander, palms, japonica, 

 camellia, asparagus, and orchids. 



Both leaves and stems are infested by the insect, which resembles 

 the olive scale (Fig. 6e) ; from the latter it may be distinguished by its 

 light brown colour and smooth surface, there being no ridges ; the longest 

 diameter of the adult female is one-seventh of an inch. Between 500 

 and 1,000 eggs are laid by each female, and the life-cycle is completed 

 in about six months ; the young insects settle along the main leaf- veins. 



TURTLE SCALE (Coccus liesperidum ) . - - This widely-distributed 

 insect, though common in hot-houses and out of doors in the warmer 

 parts of the Dominion, is not especially injurious, except for the copious 

 honey-dew secreted and the consequent sooty mould; it occurs on holly, 

 ivy, camellia, citrus, laurel, myrtle, oleander, and japonica. 



The insect infests leaves and stems, and is especially abundant on 

 succulent growth. The adult female is rather reddish-brown in colour, 

 dome-shaped, but with the margins flattened on the host plant; on each 

 side the margin is notched by a shallow depression, and there is a deeper 

 one at one end; over the surface is a reticulation of ridges, resembling 

 the pattern on the back of a turtle ; fully-developed individuals measure 

 from one-sixth to one-eighth inch in diameter. This species is vivi- 

 parous, and development to the adult occupies about nine weeks; there 

 may be three or four generations each year. 



FRUIT LECANIUM SCALE (Eulecanium corni). This European 

 insect is common throughout the Dominion, where occasionally it 

 becomes epidemic and causes some temporary damage; with it are 

 associated honey-dew and sooty mould. Among the plants infested are 

 apricot, peach, nectarine, plum, pear, grape-vine, wistaria, raspberry, 

 mulberry, blackberry, gooseberry, black currant, ferns. 



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