How do stomach poisons operate to kill pests?

Stomach poisons operate primarily through ingestion because they are designed to be consumed by the pest as a food source. When a pest ingests these poisons, the active ingredients disrupt essential physiological processes, ultimately leading to the pest's death. This method capitalizes on the pest's natural feeding behaviors, ensuring that the toxic substance effectively enters their digestive system.

In contrast, other methods like inhalation, contact, and dermal absorption involve different entry routes into the pest's body. Inhalation refers to toxins entering through the respiratory system, while contact poisons affect pests upon physical contact with their body surfaces. Dermal absorption allows substances to penetrate through the skin, which is not how stomach poisons are designed to work. Thus, the key mechanism for stomach poisons is their ability to act once the pest ingests the toxic material, making ingestion the correct answer.