684 Insect, Fungus and other Pests. [feb., 



measures are not possible. For prevention it has been sug- 

 gested that, at the time of breeding, the male fertilising material 

 would be destroyed by adding some poison to the water. 

 Apart from the fact that fertilisation is not limited to a short 

 period, but may continue during summer, there are other 

 difficulties in the way. 



In the treatise of Sellius no fewer than 600 ointments or 

 oils are mentioned as having been tried in vain in attempts 

 so to treat the wood as to render it proof against Teredo. 

 For this purpose creosote is sometimes used, but although 

 this material may afford some protection for a short time 

 it cannot be relied on. For example, Jeffreys quotes a case 

 where in Christiania Harbour the piles had been thoroughly 

 creosoted at the rate of 10 lb. to the square foot, and yet in 

 two years, in spite of the saturation with creosote, the piles 

 were riddled by Teredo. 



Treating wood piles with water glass (liquid silicate of 

 potash) has been tried, and the use of silicate of lime or other 

 dressings used to protect stonework has been suggested. 

 Exposed piles have had nails driven into them all over, with 

 the heads very close together. The rust or iron crust which 

 results is believed to afford some protection, but if the layer 

 is thin or if it peels away the tiny Teredo fry gain entry through 

 the chinks between the nail heads. 



Copper sheathing is protective, and piles have been success- 

 fully protected by casing them in wooden boxes-, the inter- 

 vening space being rilled in with cement. 



The Engineer to the Sydney Harbour Board recently reported 

 on a method of sheathing iron bark timber with yellow metal. 

 Iron bark sheathed with Muntz metal had been in use for 

 fifty years and the timber still remained sound. It was 

 found, however, that the Muntz metal supplied recently had 

 not lasted, and the decay has been ascribed to the electrolytic 

 process by which copper is now produced. It is therefore 

 advised ^that navy brass should be used with the addition of 

 1 per cent, of tin. 



jf In the case of a pier where it was found that wooden piles 

 were continually being destroyed by Teredo, wood had ulti- 

 mately to be done away with, and the pier-props now consist 

 of cement with an iron core. 



