GARDEN PESTS IN NEW ZEALAND 



Thrips. 



The foliage of many plants is sometimes infested by very minute 

 black insects, known as thrips. ' A species commonly met with is 

 that found upon ripe peaches. Thrips are readily identified by the 

 structure of the wings (Fig. 8, 4), which are but narrow strips fringed 

 with long, rigid hairs. These insects, by puncturing the plant tissues 

 and sucking up the nutrient sap, very often are responsible for infecting 

 healthy plants with disease, such as mosaic. 



According to the species of thrips, the female lays her eggs either 

 in the plant tissues or upon the surface. The young insects are wing- 

 less, but attack the plant in the same manner as does the adult; as 

 development proceeds, the insect transforms to a pupa, from which the 

 adult ultimately emerges. A characteristic symptom of thrips infesta- 

 tion is a silvering of the foliage, while the leaves are further rendered 

 unsightly by the minute specks of hardened excreta ejected by the insects. 

 Many thrips pass their, whole development upon the host plants, while 

 others pass part of their lives underground. One' of the commonest 

 species met with under glass and out of doors is the greenhouse thrips 

 (Heliothrips liasmorrUoidalis). Thrips are readily controlled by means 

 of nicotine-sulphate. 



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