Technical Abstract: A field test was conducted whereby adult Tribolium confusum (DuVal), the confused flour beetle, were exposed with 0 to 2,000 mg of flour to a pyrethrin-carbon dioxide aerosol inside an open abandoned warehouse. Applications were made according to label directions, and beetles were exposed to the aerosol for 2 hours. After exposure, knockdown was assessed, and beetles were held for two weeks either in the same dishes in which they were exposed or transferred to new dishes. Resident insect populations inside the test warehouse and outside were assessed through the use of pheromone traps. Virtually all beetles were knocked down upon removal from the exposure environment. Recovery from knockdown increased with the presence of flour, and varied depending on the position of the exposure dishes inside the warehouse. Recovery was also greater for those beetles transferred with the flour that had been exposed to the aerosol compared to ones that were transferred to clean dishes. Inside the warehouse, Plodia interpunctella (Hübner), the Indianmeal moth, and Trogoderma variabile (L.), the warehouse beetle, were the major species collected in pheromone traps. Large numbers of T. variabile were captured outside the warehouse, but their numbers declined during the study, while captures of P. interpunctella outside remained relatively constant. The intermittent aerosol treatments did not seem to affect these resident populations.