What is the primary characteristic of systemic pesticides?

The primary characteristic of systemic pesticides is that they move within the plant. This means these pesticides are absorbed by the plant through its roots or leaves and are translocated throughout its system. As a result, they can effectively control pests that feed on various parts of the plant, including those that might not come into direct contact with the pesticide application. This internal movement allows systemic pesticides to provide protection not only on the surface but also internally, effectively managing pests that would otherwise evade contact insecticides.

In contrast, other options highlight characteristics of different pesticide types or application methods. For example, the pesticides that kill pests on contact only act on the surface and require direct exposure to be effective, while those with a short life in the environment do not persist long enough to have a systemic effect within the plant. Similarly, pesticides that act only on the surface of the soil do not possess the ability to be absorbed and move within the plant, which is a crucial feature of systemic pesticides.