13 
Similar treatment should be given to the doors and all other natural 
outlets, including the chimneys, fireplaces, flues, registers, ventilators, 
eracks in the ceilings and walls, and accidental apertures, such as rat 
holes in the floor. All of these should be tightly closed. 
It is always advisable that at least two persons be present for a last 
inspection before the final work of liberating the gas. Even after all 
preparations are made an outlet may sometimes be discovered that 
has escaped notice. 
To provide for quick and thorough ventilation after the process is 
completed two or more opposite windows should be left-unlocked and 
arranged, especially in the upper floors, so that they may be pulled 
down or up, as the case may be, by means of a stout cord or rope from 
the outside.? 
CLEANING THE MILL. 
As an initial step to the fumigation of a mill or other structure 
inhabited by the flour moth, it is important to clean it as thoroughly 
as possible and remove all infested flour or other mill product and 
promptly burn it, that as many of the caterpillars, pupx, and eggs 
of the insect as possible may be destroyed. Most progressive millers 
employ a system of cleaning out before fumigating, since before the 
general adoption of fumigation methods in our principal milling cen- 
ters the only recourse was to close down the mills (which it was 
found necessary in some cases to do as often as twice a week) and 
clean out everything by mechanical means. It is feared, however, 
that too often the sweepings are not properly disposed. of by prompt 
burning. 
The operation includes the cleaning of all spouts, elevator legs, 
purifiers, and other parts of the machinery and other equipment, as 
also the walls, ceilings, corners-——in fact, every portion of the building 
in which the insect could find lodgment. The reason for cleaning 
out at this time is to afford the gas a better chance to penetrate all 
parts of the building so as to kill the insects in their various stages. 
Every particle of infested flour and waste material which might harbor 
the insect or its eggs should be swept down and out until the mill 
appears to be absolutely clean. Then as soon as possible thereafter 
the preliminaries of the actual fumigation should be undertaken. 
Elevator and belt brush.—For cleaning elevators infested by the 
Mediterranean flour moth, Johnson long ago advised a brush similar 
to the one illustrated (fig. 4). It is made by taking a piece of 14-inch 
board of the same dimensions as the elevator cups, fastening the 
bristles to three sides. Side A is fastened to the elevator belt with flat- 
aThe details of arrangements are considered in Circulars Nos. 37 and 46 of this 
Bureau, which are for gratuitous distribution. 
(Cir. 112] 2 
