Methyl bromide is an excellent fumigant but has been banned because it has high potential for depleting the ozone layer which leads to many environmental and human health hazard issues. In this connection, effectiveness of carbon dioxide (CO₂, 99.9%) was studied as an alternative to methyl bromide under various exposure timings, 25 ± 1 °C, against different developmental stages of the almond moth, Cadra cautella, and red flour beetle, Tribolium castaneum. In case of C. cautella, the LT₉₉ against adult, pupa, and larval stages was achieved after 37.5, 78.1, and 99.9 h of CO₂ application, respectively. While for T. castaneum, the LT₉₉ values were obtained after exposure timings of 29.3, 153.9, and 78.4 h against adult, pupa, and larval stages, respectively. Adults were very susceptible; in contrast, pupae and larvae were more tolerant. The susceptibility order was observed as follows: T. castaneum adult > C. cautella adult > C. cautella pupae > T. castaneum larvae > C. cautella larvae > T. castaneum pupae. This study could be useful in developing the management strategies to prevent stored dates from C. cautella and T. castaneum infestation.