INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 481 



FUMIGATION 1 " 



Fumigation consists in the generation and uses of gases to kill 

 pests. Formerly such practices were limited to the uses of carbon 

 bisulfid, sulphur dioxid and tobacco fumes. The use of hydrocyanic 

 acid gas in citrus orchards has lately been so perfected as to become 

 of very great importance and has opened up a remarkable field in 

 the control of orchard pests. 



CARBON BISULFID 



Carbon bisulfid is a liquid which evaporates into a heavy, highly 

 inflammable and explosive gas. It was first used for fumigating 

 beans, grains or cereals for weevils, and is still a very efficient method 

 of controlling such pests. In handling the liquid great care should 

 be taken to keep it away from a flame on account of the vapor being 

 highly explosive. 



FOR STOREHOUSE PESTS 



Before fumigation is begun care should be taken to see that the 

 room or container is made as tight as possible. The temperature 

 should be 70 degrees Fahrenheit or above, for poor and unsatisfactory 

 results are sure to follow even excessive doses at a lower temperature. 

 In a tight compartment, 5 pounds of carbon bisulfid to every 1,000 

 cubic feet of air space will give excellent results in killing weevils. If 

 the compartments can not be made tight, increase the amount of the 

 fumigant. 



FOR ROOT PESTS 



Carbon bisulfid has also been used in the fields to kill root pests like 

 the woolly apple aphis, black peach aphis, grape phylloxera, white 

 grubs, root-maggots, but is far too expensive to be practical and is 

 effective only in soils of just the right degree of porosity. For a small 

 plant, a hole is made in the ground near the base and a teaspoonful 

 of the liquid poured into the hole, which is covered to prevent surface 

 evaporation. For larger plants several holes are made deep enough 

 to allow the vapor to disseminate around the infested roots. A syringe- 

 like instrument is sometimes used to inject the liquid into the soil 

 around the roots of the infested plants. In all such work care must 

 be exercised in making the applications or the plants may be killed 

 by an excessive dose or by the carbon bisulfid coming in direct contact 

 with the roots. 



FOR WOOD-BORERS 



Carbon bisulfid is also injected into the burrows of wood-boring 

 insects with some success, but this method has never met with much 

 favor, perhaps because in many cases the burrows are open only 

 after the damage has already been done and the insects escaped. 



833 For further information relative to fumination, see 



Bui. No. 76, Bur. Ent., U. S. Dept. Agric. Exp., by A. W._Mo 



Bui. 



Bui. 



Bui. -. 



Bui. No. 152, Cal. Agrcl. Exp. Sta., by C. W. Woodworth. 



Circular No. 11, Cal. Agrcl. Exp. Sta., by C. W. Woodworth. 



Circular No. 50, Cal. Agrcl. Exp. Sta., by C. W. Woodworth. 



31—13664 



1. No. 76, Bur. Ent., U. S. Dept. Agric. HJxp., Dy A. w. morriii 



1. No. 79, Bur. Ent., U. S. Dept. Agric. Exp., by R. S. Woghnn. 



1. No. 90, (Part 1) Bur. Ent., U. S. Dept. Agric. Exp., by r;. S. Woglui 



1. No. 90, (Part II) Bur. Ent., U. S. Dept. Agric. Exp., bj K. S. WoglUi 



