52 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



grass underneath the trap, or else hanging to the trap billets. 

 The sawdust-and-bark trap was also tried, but was not found to 

 be successful. The bark dried up so readily under the rays of 

 the sun that it had to be changed frequently ; the sawdust also 

 lost its resinous odour. The Scots pine branch es-and-bark trap 

 also gave very poor results. After experimenting with these 

 three traps, it was decided to use the billet trap only. 



During the daytime the weevils could be observed climbing 

 the trees, gnawing their way as they went. If one weevil was 

 detected on the tree, the observer was pretty certain to find 

 another, or perhaps two, in the grass at the bottom of the tree. 



The Japanese larch, being i-year 2-year plants, suffered most 

 from the weevil, some of these trees having their bark gnawed 

 off right up to the tip. European larch and Douglas fir (2-year 

 2-year) were also badly attacked. The Scots pine were fine 

 strong plants (2-year 2-year), and therefore did not suffer so 

 much. Norway spruce were likewise only slightly damaged. 



After sampling these species the weevil tried Thuya giganfea, 

 but did not relish it, also Sitka spruce with the same result. 

 The grey and common alder suffered very slightly. The traps 

 set amongst the alders yielded about two weevils per day, 

 whereas the traps amongst the Japanese larch yielded fifty to 

 seventy per day, when the pest was at its height in June. 

 American larch suffered very slightly, while ash was not 

 touched at all. 



From the beginning of June until the end of July, nearly 4000 

 weevils were trapped, by 200 billet traps. In the month of June 

 3200 were trapped, whereas the '' catch " for July only amounted 

 to 650. Adults of Myelophilus piniperda were also found on 

 the traps. 



The beetles bred out from the stumps of the last crop of trees 

 on the area, some of the flight holes being quite fresh this year. 

 They have also flown from adjoining woods of Scots pine where 

 trees have been cut out lately. 



By way of combating the outbreak, pits were dug at intervals 

 over the area into which Scots pine billets were driven, leaving 

 the ends of the billets projecting a few inches. The pits were 

 then filled up in the following way. A layer of Scots pine 

 branches was first of all put in with the ends of the branches 

 protruding, followed by a layer of soil 3 or 4 inches in thick- 

 ness. This was repeated until a mound was formed. The 



