Excerpts from the report: Development of practical methods of measuring fumigant gas concentrations by thermal conductivity, and the phenomenal growth of the recirculation method of grain fumigation, have provided much information on penetration, distribution, and sorption of methyl bromide in stored products. To give additional meaning to the gas concentration data so accumulated, laboratory tests were conducted to determine relationships between concentration, time, and mortality for representative stored-product insects in recirculators filled with different kinds of grain. Experimental fumigations of different kinds of grain with methyl bromide were conducted in laboratory recirculators to determine concentrations required to kill test insects. Gas sorption by the grain was determined by thermal conductivity analyses of gas in the fumigated grain mass.