l8o TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



25. An Infestation by Pine Weevil {Hylobius abietis). 



By Donald iMacdonald. 



On an estate in the south of Scotland two separate areas had 

 been planted in clumps, by " pitting," the one area with 2-year 

 2-year-old plants of Scots pine and spruce, and the other with 

 2-year 2 year-old plants oS. Laj-ix europaa and L. leptolepis. There 

 is a difference of one year in age between the two plantations, 

 the second having been planted in the autumn preceding the 

 attack. Both stand on areas from which a mature crop of 

 Scots pine, about 90 years old, had been cut, and in both cases 

 a forest of spruce and Scots pine more or less surrounds the 

 plantations. The total area of the two plantations is approxi- 

 mately 36 acres. 



The presence of the Pine Weevil {Hylobms abietis) was first 

 discovered on 13th May 1908, when the plantations were found 

 to be not uniformly infested. Those parts where the grass grew 

 longest were most severely attacked, this being apparently due 

 to the susceptibility of the weevils to variations of temperature. 

 On cold raw days, or days with hot sun, fewer were to be found 

 than on other days. On warm sunny days the beetles were 

 found feeding most frequently from 10 till about 11.30 a.m., 

 when they disappeared, not returning to resume their feeding 

 till about 2.30 P.M. They are also sensitive to cold, being less 

 numerous and less virulent in their attacks in cold seasons than 

 in more genial ones. 



They appear to be strongest in flight during June and July. A 

 fellow-workman here, while standing among logs of timber at 

 this season, was struck by a flight of beetles, two of which attached 

 themselves to his clothes, and proved to be weevils. This flight 

 doubtless contained beetles of the current and the preceding 

 years, in search of suitable breeding-places. It is obvious that 

 at such seasons trenches with perpendicular sides, sometimes 

 recommended as a preventive of the attacks of the beetles, could 

 be of no value whatever. 



Remedial Measures Adopted, 



I. Satcidiist Traps. — Numerous traps were laid by spreading 

 layers of fresh sawdust at regular intervals between the lines of 

 plants, and covering these over with fresh slabs and bark of 

 Scots pine. The weevils were gathered from the traps every 



