What type of pesticide might require only a few ounces to be lethal?

The type of pesticide that might require only a few ounces to be lethal is highly toxic pesticide. Highly toxic pesticides are designed to be very effective at low concentrations, meaning that even small amounts can lead to severe effects, including lethality. These pesticides are formulated to target pests efficiently, often containing active ingredients that are potent enough to disrupt biological processes in insects (or other target organisms) with minimal application quantity.

In contrast, moderately toxic pesticides generally require more significant amounts to cause harmful effects, while slightly toxic and non-toxic pesticides are formulated to be safer for application around humans and animals. Slightly toxic pesticides may cause mild effects but typically do not pose a serious risk at low dosages. Non-toxic pesticides are designed to have little or no harmful impact, which is evident in their intended application for safety in various environments. Therefore, while moderately toxic pesticides do have the potential to cause damage, the phrase "only a few ounces to be lethal" aligns more closely with characteristics of highly toxic pesticides.