Which formulation involves solid material that evaporates over time to control pests?

Impregnates are formulations that consist of solid materials that have pesticide active ingredients incorporated into them. These formulations, when applied, gradually release the active ingredients over time as they evaporate. This slow release is particularly effective in providing long-lasting pest control, as it allows the active ingredients to persist in the environment, giving them an extended action against pests.

In contrast, fumigants are gases designed to penetrate and eliminate pests in enclosed spaces, while pesticide-fertilizer combinations are mixtures that provide both nutrients and pest control, but do not operate on the same principles of evaporation. Animal systemics work differently by entering the system of the animal and offering protection from pests, rather than releasing pesticides as a solid evaporates. Therefore, impregnates are the formulation type that specifically employs solid material evaporation for pest control.