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Simple Summary: The red flour beetle is the most destructive pest of stored grain commodities, including flour, food grains, biscuits, pasta, nuts, cereals, and beans. Warehouse owners mostly use fumigants to control its infestation; however, these fumigants are toxic. The Indo–Pakistan region is rich in certain plant species that have repellent or deterrent effects on insects, and these plants are safer for humans. Among these plants are Mexican tea, long leaf Indian pine, rattan pepper, garden cress, neem, Baccharis teindalensis (a Columbian native herb also found in Pakistan), and marjoram. Hence, in the present study, we determined the toxic effect of these essential oil extracts against red flour beetle. The toxicity and repellent activities of these plant oils were determined through four-arm olfactometer bioassays. Mortality was recorded 1 day, 2 days, and 3 days after oil extract exposure. Data were analyzed using statistical software. Means were compared through LSD at the 5% level of significance. Overall, Mexican tea and Indian native palm oil were effective repellents. This study concludes that Mexican tea and Indian native palm oil can be used as alternative repellents against red flour beetle infestation. Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) is the most destructive pest of stored grain commodities. To control the attack of this insect pest, it is important to develop non-hazardous alternatives to replace fumigants. This study examined the fumigant toxicity and repellent activity of seven essential oils (Chinopodium ambrosiodes, Pinus roxburghii, Zanthoxylum armatum, Lepidium sativum, Azadirachta indica, Baccharis teindalensis, and Origanum majorana) against adult T. castaneum under controlled laboratory conditions. The fumigant toxicity and repellent activities of essential oils were tested using five different doses (62.5, 125, 250, 500, and 1000 µg) in vapour-phase fumigation and four-arm olfactometer bioassays, respectively. In vapor-phase fumigation bioassays, mortality data were recorded after 24, 48, and 72 h. The results showed that C. ambrosiodes and P. roxburghii essential oils are potential fumigants against adult T. castaneum. In repellency bioassays, a one-week-old adult population of T. castaneum was used to test the repellency potential of the essential oils. The results indicated that C. ambrosiodes and P. roxburghii had significant repellency potential against T. castaneum. Overall, we conclude that these essential oils have strong repellent and fumigant properties and can be used as potential repellent compounds to deter the insects. [ABSTRACT FROM AUTHOR]