8 CIRCULAR 3 6 9, U. S. DEPARTMENT OF AGRICULTURE 



Buildings of more than one story are usually fumigated with each 

 floor as a separate unit. In such cases all openings between floors 

 must be closed, especially where pieces of machinery extend from one 

 floor to another. Doors leading to the elevator shaft should also be 

 carefully sealed by stripping the edges or by stuffing sacking into all 

 cracks. If the elevator door is of the type that rolls upward, a 

 wooden frame covered with reinforced waterproof paper, forced into 

 place against felt gaskets, provides an excellent seal (fig. 11). 



Machinery that is used to pack, mix, or handle foodstuffs in any 

 way should be opened as completely as possible and all accumulations 

 of materials removed. Most fumigants do not penetrate for more 

 than a few inches into flour, meal, or similar foodstuffs ; hence, such 

 accumulations, if left in the machinery, protect insects from the 

 effects of the gas. Accumulations of waste material under or around 



Figure 10. — Doorway between compartments in modern concrete storage warehouse 

 sealed for fumigation. Framework of 2- by 4-inch lumber, covered with heavy fiber- 

 reinforced waterproof paper, forced against strips of heavy felt padding. The fire- 

 proof doors have been rolled back. Note the small door, which also shuts against felt 

 gaskets, for the use of fumigators. A glass window has proved useful in permitting 

 inspection of operations. 



machinery, in feed bins, or in any part of the building should also be 

 removed and sold or destroyed before fumigation. 



Commodities in warehouses or storage rooms should be so arranged 

 as to provide the maximum circulation of the f umigant ; large, solid 

 stacks of bagged material should be avoided. In sections that are 

 divided into small compartments or storage rooms, the connecting 

 doors should be opened to allow a proper distribution of the gas. 

 Where sections of a floor are large, as in many metropolitan storages, 

 each section may be fumigated to better advantage as a single unit. 



DESIRABILITY OF A HIGH TEMPERATURE DURING THE FUMIGATION 



It is desirable to maintain a fairly high temperature in the build- 

 ing during the fumigation. Insects are not very active at tempera- 

 tures below 60° F., and they become more or less dormant at 50° or 

 below. In the dormant state they are extremely difficult to kill with 

 fumigants. At 75° they are active and their susceptibility to the 



