What is indicated by the term 'residual' in pest control products?

The term 'residual' in the context of pest control products refers to the lasting effect that these products have after application. Specifically, a residual pesticide continues to remain effective over a period of time after it has been applied, meaning it can control pests even after its initial application. This characteristic allows for longer-lasting pest management, reducing the need for frequent reapplication, which can improve efficiency and effectiveness in pest control practices.

In contrast, options suggesting that a residual pesticide is a temporary solution or is only effective in specific conditions do not accurately capture the essence of what 'residual' means. Similarly, the notion that it should be applied frequently contradicts the very definition of residual efficacy, as a true residual product is designed to provide ongoing effectiveness without the need for constant application.