What is the main difference between contact and ingestive pesticides?

The distinction between contact and ingestive pesticides is essential in pest management and understanding how these products function. Contact pesticides operate by killing pests upon direct contact with the surface where the pesticide has been applied. When a pest crawls over or comes into direct contact with the pesticide, it absorbs the chemicals through its exoskeleton or outer body, leading to its demise. This method is effective for managing pests that come into contact with treated surfaces.

The other options do not accurately reflect the characteristics of contact and ingestive pesticides. While it might be true that some contact pesticides can be formulated to be safer for humans, this is not universally applicable to all contact pesticides. Ingestive pesticides are specifically designed to be consumed by pests; therefore, stating that ingestive pesticides are used on crops oversimplifies their role as they can pose risks to non-target organisms that ingest them. Lastly, the environmental impact of pesticides cannot be generalized in such a manner, as both types can have varying degrees of environmental friendliness depending on their formulation and application context. Thus, the primary distinction remains that contact pesticides kill through direct contact, while ingestive pesticides function by being ingested by the pests.