52 ANNUAL REPORTS OF DEPARTMENT OF 
most Important pests of stored -rain, and although it is disagreeable to handle ir 
has some advantages over other commonly used fumigants, The application of 
tnmigants to the top of the bin and at tour Levels when the bin was being filled 
with the ethylene oxide-solid carbon dioxide mixture was found to give an era 
satisfactory kill. 
An investigation of the fundamental principle underlying vacuum fumigation 
of cereal products in which the ethylene oxide-carbon dioxide mixture was used 
as the fumigant was initiated during the year at Cedar Rapids, Iowa. Results 
so Car in this investigation have indicated that the quantity of gas required for 
successful results in the fumigation of rice and possibly ether product- depends 
upon the quantity to be fumigated rather than on the cubic feet of space B 
culation of the fumigant in the vacuum tank adds greatly to its efficiency, reduc- 
ing by 25 percent the dosage required when recirculation is not practiced. A 
carefully conducted series of experiments to determine the distribution of the 
fumigant in a vacuum chamber revealed that selective absorption takes place iii 
the vicinity of the gas entry point and that multiple entry points give a more 
uniform distribution of the fumigant than only one. This improvement is DOW 
being utilized in commercial vacuum tanks. 
A study of the sterilization of Hour products by heat has indicated that bags 
flour can lie completely sterilized in 24 hours and that only a few hours are 
required for smaller bags, ;it vault temperatures of from ]7<> : to 185 F. Pre- 
liminary results have also determined that a fan larger than that ordinarily used 
is necessary for effective circulation of the heated air in the vault and that best 
results can be obtained by attaching it near the ceiling. Tests also have indi- 
cated that forced circulation is of considerable value in raising the temperatures 
in the interstices between large bags in the vault. 
Extensive observations have been made on the distribution and extent of in- 
festation of various stored-produet insects in mills in the Middle West and on 
the effectiveness of various commercial practices utilized in insect control. 
EUROPEAN CORN BORER INSPECTION AND CERTIFICATION 
INSPECTION AND CERTIFICATION 
Federal inspection and certification continued with the personnel nee- 
to fulfil] the quarantine requirements of States prescribing Federal rather than 
State certification as a requisite for admission of host material likely to spread 
the European corn borer. Inspectors covering large districts were stationed in 
Indianapolis, Ind.. Detroit. Mich., and Toledo. Ohio. Inspections in territory 
jointly affected by Japanese beetle and. or gypsy moth restrictions were made 
by inspectors working from numerous districts and suboffices in the overlapping 
areas. 
F..r the second consecutive year there was an increase in the quantity of 
certificates Issued in conformity with the respective state quarantine orders. 
Inspectors issued 22,133 certificates to authorize the movement of commodities 
having an estimated value of $165,293. General improvement in the nursery 
trade, with a greater movement of dahlia roots, accounted for much of this 
increase. 
State com borer quarantines or orders remained unchanged during the year. 
Federal Inspection continued as a requirement for the entry of restricted com- 
modities into Arizona. California. Colorado, Georgia, Louisiana, Nevada. Oregon, 
Texas, and Utah. Wyoming maintained its embargo against the entry of host 
mate! La] from | be infested States. 
STATE COMPULSORY < I t LN i P ACTIVITIES 
Working under the direction of the Wisconsin Department ^( Agriculture, 
farmers in that State cleaned up Qelds that Works Progress Administration 
-coin-, working under State supervision had found Infested with the corn borer 
during the summer of 1935. The farmers were paid $2 per acre tor cleaning 
up their Infested fields, This work, performed in addition to the regular cul- 
tural practices, consisted of picking up and burning all pieces of cornstalks 
remaining above ground after the Held had been cultivated and seeded to sniall 
grain or corn. 
