I20 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



abundant, and in certain localities is accompanied by 



T. acuminatus. 

 5. The tree is deserted except by ants, fly larvae, centipedes, 



spiders, etc. 

 Such is a brief history of the invasion of a Scots pine by its 

 enemies. Now this sequence of insects is a very important 

 point in forest protection. Its moral undoubtedly is, the longer 

 you neglect to adopt preventive and remedial measures, the 

 more pests you are going to have to fight. So far only the 

 occasional sickly stem has been considered, and it may be 

 argued that sickly stems are easily removed and the wood 

 thereby freed from further infection. This is largely true. 

 There is, however, another aspect of the case, and it is this, 

 that the Scots pine clearing is exactly comparable to the sickly 

 standing stem as regards insect attack. That this is so is shown 

 by the following summary of observations made on felled Scots 

 pine areas during the past four years. A comparison of this 

 summary with that given for the stem shows a striking similarity. 

 The stem in this case is reduced to the stump. The crown, 

 branches and roots, however, remain as before. 



1. On the stump, M. piniperda. 



2. On the stump, M. piniperda and H. palliatus. 

 On the roots, H. abietis. 



3. On the stump, H. palliatus. 



On the roots, H. abietis and H. ater. 

 On the branches, P. bidentatus. 



4. On the stump, a few II. palliatus. 



On the roots, H. abietis and H. ater. Both now attack- 

 ing the smaller roots deep in the ground. 



5. P. bidentatus, abundant. H. ater, few. 



6. Stumps, roots and branches deserted except by ants, 



centipedes, etc. 

 The period of time from the first to the last stage in this 

 sequence is from three to five years, according to the age of the 

 trees when felled, the wetness or dryness of the soil, and the 

 weather conditions. 



Stage I begins immediately on felling. 

 Stage 2, nine months to a year later. 

 Stage 3, six to nine months later ; while 

 Stages 4, 5 and 6 follow in the next year and a half to two 

 years. 



