What is a key characteristic of systemic insecticides?

Systemic insecticides are defined by their ability to be absorbed by the plant, which then distributes the chemical throughout its tissues. This characteristic allows the insecticide to affect feeding insects that consume parts of the plant, such as leaves or stems. When insects feed on these treated areas, they ingest the insecticide and are subsequently affected by it.

This mode of action makes systemic insecticides particularly useful in controlling pests that may be difficult to manage with contact insecticides, which only affect insects when they come into direct contact with the chemical. Because systemic insecticides are absorbed internally, they can provide more extended protection against pests that feed on the plant for longer periods.

While other options may refer to characteristics of different classes of pesticides, they do not align with the fundamental nature of systemic insecticides as they focus on contact action, general effectiveness against all pests, or residual effectiveness, which does not specifically highlight the absorption and internal distribution features of systemic products.