What is a residual pesticide?

A residual pesticide is defined as a type of pesticide that breaks down slowly and remains effective over an extended period. This prolonged effectiveness is due to its ability to adhere to surfaces and continue providing pest control long after initial application. Residual pesticides are particularly beneficial in situations where ongoing pest management is necessary, as they can continue to act upon pest populations even after the initial application has dried or settled.

In contrast, options that describe pesticides that lose effectiveness quickly or are only effective on contact focus on characteristics that do not pertain to residual effectiveness. While pesticides used only by professionals or those with specific application requirements have their context, they do not define the residual quality of a pesticide itself. Therefore, the defining feature of a residual pesticide is its slow breakdown and lasting efficacy.