TERMITES IX THE UNITED STATES. 29 



I). ('., this course was finally adopted, with the result that white 

 ants were completely excluded and their work terminated (Marlatt). 

 This measure was also necessary in the case of the buildings of the 

 State Agricultural College at Manhattan, Kans., where wooden 

 partitions, floors, and other woodwork were torn out and cement 

 floors and walls substituted. 



If the foundation of the building is such that damage to the wood- 

 work is extensive and likely to recur, and it is impracticable to 

 replace with concrete or stone, it is advisable to replace the exposed 

 interior woodwork with wood impregnated by a 6 per cent solu- 

 tion of zinc chlorid or a 1 per cent solution of bichlorid of mercury ; 

 except in case of flooring in contact with the ground or in wet situa- 

 tions, where such preservatives would leach out. 



In case of greenhouses iron frames and concrete work should, 

 wherever possible, replace woodwork, and woodwork should be im- 

 pregnated with bichlorid of mercury. Wood impregnated with this 

 preservative can be painted after treatment. 



In some cases thorough and repeated drenching of infested tim- 

 bers, where accessible, with kerosene oil may afford temporary relief 

 and kill some of the white ants. Kerosene oil should be poured into 

 the crevices through which the winged insects emerge from infested 

 wood. As the insects may have entered the house through soil chan- 

 nels by means of pillars or the supports of porchings and steps, these 

 last should be removed if damaged and 'the ground soaked with 

 kerosene. 



OTHER TIMBER IN CONTACT AVITH THE GROUND. 



Poles, 1 mine props, 2 railroad ties, posts, construction timber, and 

 other wood in contact with the ground should, since these insects attack 

 all classes of wood to which they can attain access from the ground, 

 be treated with chemical preservatives to render them more resistant 

 to termite attack. Superficial methods, temporarily prolonging the 

 length of service of timber, include brush and dipping methods of 

 treatment. From experiments it has been determined that for timber 

 in contact with the ground brush and dipping treatments with coal- 

 tar creosote will render southern yellow pine resistant for at least 

 two to three years in the Southern States and effective for from three 

 to four years and longer. Under the closed-cylinder pressure process 

 ("full cell" treatment) of impregnation of southern yellow-pine 

 timber with coal-tar creosote, at least 16 years' service is attained in 



1 Snyder, T. E. Insects Injurious to Forests and Forest Products. TJ. S. Dept. Agr. 

 Bur. Ent. Bui. 94, pts. 1-2, 85 p., 16 pi., 14 fig., 1910-1915. Damage to Telephone and 

 Telegraph Foles by Wood-boring Insects. U. S. Dept. Agr. Bur. Ent. Circ. 134, 6 p., 

 3 fig., Mar. 7, 1911. 



2 Snyder, T: E. Insect Damage to Mine Props and Methods of Preventing the Injury. 

 U. S. Dept. Agr. Bur. Ent. Circ. 156, 4 p., July. 13, 1912. 



