PROCEEDINGS OF THE THIRD ENTOMOLOGICAL MEETING 701 



attack, and a slight growth in height is obtained, but the resulting tree 

 is SO much forked as to be useless for timber. 



The weak link in the seasonal history of the insect occurs in the 

 first two broods. In the absence of the flowers or fruit of toon or of 

 mahogany and other Meliaceous trees, these generations are very serious- 

 ly checked. Shoots are not produced during this period by the host- 

 trees except in insufficient quantity and the incidence of the pest suffers 

 a very considerable reduction, which may amount to a complete 

 hiatus. 



We have therefore a simple protective remedy. In order to estabHsh 

 a toon or mahogany plantation, it is sufficient to remove all flower- 

 bearing host trees in the neighbourhood. If it is necessary for sylvi- 

 <;ultural or other reasons to retain these trees, another measure must 

 be adopted. A protective barrage must be established round the site 

 of the plantation or regeneration area, by sack-banding the flower in» 

 trees and destroying the toon moth larvae in the forest, just as codling 

 moth larvae are destroyed in fruit orchards. 



Later, when the young trees have grown up and begin to flower 

 the pest may gain a foothold. But, during this period the methods of 

 crop production, which aim at prolonging the height growth and checking 

 the tendency to crown expansion and flowering, are also methods of 

 crop protection. They may be assisted, if vitally necessary, by sack- 

 banding during the first two generations. Towards the end of the life 

 of the crop when it is opened out for diameter increment, and possible 

 natural regeneration, sack-banding will be necessary annually. That 

 particular problem will arise in some fifty or sixty years time and may 

 safely be left to the Entomological Service of the period. 



The case of the toon shoot borer with its successive generations of 

 different habits is analogous to that of many important lepidopterous 

 defoliators. The notorious teak defoHators, Pyrausta machoeralis, 

 H'ljhlcea puera and their associates, do not pass the whole of their seasonal 

 history on teak. The times of leaf-flush and leaf-fall vary in different 

 parts of its habitat, and in those locahties where teak comes into leaf 

 late the defoliators develop a,^ least one brood on other food-plants. 

 We are now endeavouring to discover the foodplants of these defoHators 

 -and their preferences ; but investigations so far have shown that the 

 defoliation of teak is produced by a truly bewildering complex of 

 Noctuids, Pyralids, Arctiads, Curculionids and Melolonthids ; which 

 seems to indicate that we have undertaken to investigate the habits 

 ■ of a large portion of the insect population of the forest. 



Leaving the Lepidoptera, an example may be cited of the problems 

 \presented by the Coleoptera, 



