As a result of the Montreal Protocol, methyl bromide, a major fumigant for the food industry, is facing a mandatory 100% production and import phase out. Millers, food processors and fumigators are looking for replacements. Sulfuryl fluoride is one replacement strategy that was recently labeled for the food market. This presentation summarizes research that is underway to compare the effectiveness of sulfuryl fluoride and methyl bromide under real world conditions. Since 2005, five methyl bromide and nine sulfuryl fluoride fumigations have been completed in four U.S. flour mills. All life stages (eggs, larvae, pupae, and adults) of two major pest species, Indianmeal moth, Plodia interpunctella (L) and red flour beetle, Tribolium castaneum (Herbst) were used in bioassays exposed during fumigations. Insect monitoring (moth flight and flour beetle dome traps) was conducted before and after the fumigations to determine the existing pests population and rebound rates. Current bioassay results indicate 100% mortality of larval and adult stages of both species for both fumigants. More than 99% of RFB and 100% of IMM pupae died when exposed to either fumigant. The majority of red flour beetle larvae from treated eggs died before the adult stage (95.36% Sulfuryl fluoride and 99.67% Methyl bromide) as well as Indianmeal moth eggs (96.56% Sulfuryl fluoride and 99.67% Methyl bromide). Insect populations were usually significantly lower right after fumigation but could increased to pre-population level within 2-8 weeks depending on the facility.