AN INFESTATION BY PINE WEEVIL. l8l 



morning. The success of this method depends entirely upon 

 the attraction exercised upon the weevils by the oils of the 

 sawdust and the cambium. It proved disappointing, and was 

 only continued as a measure subsidiary to the more fruitful 

 method of hand-gathering. 



2. A Proprietary Insecticide. — A well-known and much 

 advertised insecticide was then tried. It takes the form of a 

 viscous substance which was painted on the stems of the plants 

 over about an acre of ground. This had no appreciable effect, 

 as the plants treated continued to show fresh weevil marks ; the 

 method was therefore discontinued. 



3. Paris Green. — To prepare this, soft soap was incorporated 

 with lukewarm water till the mixture attained a gummy con- 

 sistency, and the compound was afterwards added in the pro- 

 portion of I ounce to 2 gallons of the soapy solution. The 

 mixture was used over an acre of stems and had good results, the 

 plants treated showing few signs of insect attack. The method 

 was not, however, adopted till near the end of the infestation, 

 and it is not known how long the mixture would have retained 

 its protective qualities, nor to what extent it is fatal to the 

 insect, as no dead weevils were found after the application. It 

 may therefore simply render the treated plants distasteful. The 

 treatment was experimental only, as Paris green, like other 

 arsenical compounds, is known to be injurious to plant tissues. 

 The mixture should be made in small quantities only, should 

 be stirred before being used, and should be applied to the 

 stems only, as they are less sensitive than the leaves to its action. 

 The plants treated have apparently not suffered at all from the 

 application, and in the case of another attack from the weevil 

 here, this method will probably be more extensively used. In 

 an attack by saw-fly {Lophyrus rufus) on this property, young 

 Scots pine were sprayed, under a sweltering sun, with a mixture 

 of I oz. of Paris green to 6| gallons of water, with very 

 trifling damage to the plants (cf. Transactions, xxi. pp. 53, 54). 



4. Hand-Gathering. — This is a very simple operation ; it 

 consists in gathering the insects from the plants and the grass 

 (in which they are generally most numerous), and putting them 

 into suitable receptacles for destruction. Bottles form the best 

 receptacles, as their smooth, slippery sides prevent the insects 

 climbing out. Care and quietness are essential for success, as 

 on the slightest alarm or vibration the weevils drop from the 



