INDUSTRIAL FUMIGATION AGAINST INSECTS \) 



gases increases as the temperature rises. For best results a tempera- 

 ture of at least 75°, and preferably somewhat higher, should be main- 

 tained throughout the fumigation. 



EFFECT OF WIND VELOCITY 



The velocity of the wind during the exposure influences the effec- 

 tiveness of a fumigation. The fumigation should be conducted pref- 

 erably when there is no wind. It is a well-established fact that the 

 greater the velocity of the wind during a fumigation, the poorer 

 are the results. Apparently a strong wind prevents proper distribu- 

 tion of the gas, and air pockets are formed which the gas does not 

 penetrate and which, therefore, act as a protection to insects. To 

 break up such pockets some means of circulating the air in a building 

 during fumigation is desirable. 



Figure 11. — Opening to elevator shaft sealed ready for fumigation in same manner as 

 the doorway in figure 10. In hoth cases the sealing was done at the Naval Supply 

 Depot, Naval Operating Base, Hampton Roads, Norfolk, Va. 



CHOICE OF A FUMIGANT 



In choosing a fumigant several factors must be taken into con- 

 sideration. If the building is modern and very tight, several fumi- 

 gants can be used with success, and a choice can be governed by such 

 items as cost, efficiency, availability, safet}^ and effect upon the com- 

 modity to be fumigated. If the building is not particularly tight, 

 it will be impossible to maintain a strong concentration of any gas 

 for very long, and a quick-acting gas is the only kind that will be 

 effective. Hydrocyanic acid is the only gas available that will kill 

 quickly. 



QUANTITY OF FUMIGANT NEEDED 



The quantity of fumigant to be used will vary according to the 

 length of exposure, the temperature, the tightness of the building, 



4:>0— -:;.-, 2 



