FAMILY SCOLYTIDAE 573 



(a) Newly Felled Trees and Windfalls.— The first of these are known, as 

 they will be in felling areas. The windfalls must be searched for and 

 located. This will involve going carefully over the entire area. 



(b) Standing Sickly Trees. — Whilst searching the area for windfalls a look- 

 out will be kepi for standing sickly trees, and all such will be marked with 

 a tar ring or any other suitable mark. It cannot be hoped that all these 

 trees will have been located and marked in time to catch the first generation 

 of beetles to issue after the attack was first discovered. If, however, this 

 generation is not caught, it should be possible to have marked all these trees 

 in time to catch the larvae of the second or third generation. 



In both the above cases the trees will be left in situ until they are 

 known to be full of grubs : the approximate dates are given under the life 

 history; (b) trees are then felled and both (a) and (b) barked, and the inner 

 face of bark turned outwards so as to expose it to the sun. Both larvae 

 and pupae will be killed. Saplings and branches which are too thin to bark 

 should be stacked and burnt. None of the standing trees should, however, 

 be felled until they have become really badly infested by the beetle, even if 

 this involves leaving them standmg over two or more generations. They 

 thus serve the purpose of trap trees. 



(c) Green Standing Infested Trees.— Newly attacked green standing 

 trees are more difficult to deal with. Their removal depends entu-ely on the 

 degree to which they have been attacked and on their proximity to a bad 

 "centre" of infection. Also it is difficult to mark down these trees until 

 they commence to fade, when the bright yellow^ needles attract attention to 

 them. When any such trees are discovered it is advisable, if they are not 

 very severely attacked, to leave them standing over several generations of 

 the beetles, Vor as soon as their vitality becomes lowered to an appreciable 

 extent they will attract beetles to oviposit in them and thus serve as trap 

 trees. This will prevent the beetles from going to as yet uninfested trees. 



Trap Trees.— In order to ascertain definitely and rapidly the extent and 

 intensity of an attack, green trees in suitable positions should be chosen 

 here and there throughout the area, preferably along a road or footpath 

 where they are easily reached and felled. These trees may be chosen at any 

 time, but they should only be felled a few days before a period at which it 

 is known that a generation of the beetles will be on the wing in the forest 

 searching for trees in which to oviposit. It will be found that the beetles 

 will unerringly detect the presence of these felled trees and will oviposit in 

 them. These trees are termed "trap" trees. As soon as they are full of 

 completely grown larvae or of pupae, they should be barked and the bark 

 exposed to the sun or burnt, as may be most advisable. If a trap tree is 

 not seriously infested by the generation of the beetles issuing soon after it 

 was felled, it may be left to catch the next generation. The trees should be 

 so felled as to lie in a position sheltered from the sun during the hot portion 

 of the day. They should not be felled in dense shade, as in that event the 

 beetles will not resort to them to oviposit. 



