ON METHODS OF PREVENTING INSECT ATTACK 47 



the life history, {b) should then be felled, and (^0 and (6) barked and the bark 

 turned up so as to expose it to the rays of the sun. This will be strong enough 

 to kill off the larvae. All saplings or branches which are too thin to be barked 

 should be burnt. If, however, {b) are not badly infested with the beetle they 

 should be left standing to serve as "trap" trees for succeeding generations. 



(c) Standin>y Green Infested Trees. — It will be found that newly attacked 

 green trees are much more difficult to deal with, as their removal must 

 depend entirely on the degree to which they are attacked and on their 

 nearness or otherwise to "centres" of infection. It will also be found very 

 difficult to discover them until they are commencing to fade, when the 

 bright yellow needles of the conifers or the drying shrivelled leaves of the 

 broad-leaved species attract attention to them. It may prove advisable to 

 leave those discovered, when but slightly attacked, standing over one, two, 

 or even three generations of the insect, since there is a likelihood of their 

 serving as an attraction to further beetles to lay their eggs in. They thus 

 serve as "traps," and if used as such properly they may attract a large 

 number of beetles which would otherwise oviposit elsewhere in uninfested 

 trees. In all cases where such trees are not very seriously attacked 

 they should not be felled before the larvae of the second generation of the 

 beetle after finding them are reaching full growth. They will thus serve 

 the purpose throughout the area of "trap " trees. 



''Trap'' Trees. — In order to ascertain the extent and intensity of an 

 attack suitable green trees should be chosen here and there in the forest, pre- 

 ferably along a road or footpath, and felled. These trees should be felled 

 just before the periods at which the beetles are to be expected on the wing 

 in the forest. It will be found that the beetles will resort to these felled 

 trees to oviposit, and the trees will thus serve as "traps." As soon as they 

 are full of fully grown larvae they should be barked and the bark exposed to 

 the sun or burnt, as may be deemed most advisable. If a " trap " tree is not 

 seriously infested by the generation of the beetles issuing soon after it has been 

 felled it may be left for a following one. The trees should be so felled as to 

 lie in a position sheltered from the sun during the hottest portion of the day. 

 They must not, however, be felled in dense shade, as the beetles will not 

 resort to such trees to oviposit. In choosing these trees it should be borne in 

 mind that they must be healthy and full of sap. It will be useless felling 

 nearly dead trees for such a purpose, as they would rapidly dry and would 

 not be sought out by the beetle. The beetles require fresh sappv cambium 

 to lay their eggs in. 



The periods at which the "trap" trees and the sickly standing trees 

 should be felled and the bark stripped off and burnt will depend upon 

 the life histories of the pests you are combating. The time at which the 

 trees should be felled is at the period when they are full of completely 

 developed grubs and newly changed pupae. The latter must not be 

 allowed to mature into beetles, or the earliest maturing ones will either escape 

 from the tree before you fell, or fall out of their pupal chambers when th6 



