In what form do most fumigants exist when used for pest control?

Most fumigants exist in a gaseous form when used for pest control because they need to penetrate various materials, such as soil, building structures, or stored products, to effectively eliminate pests. The gaseous state allows these chemicals to disperse evenly and reach hidden areas where pests may reside, providing comprehensive control.

Additionally, using fumigants in a gaseous state maximizes their effectiveness because gases can diffuse and fill space more effectively than liquids or solids. While some fumigants may be stored or transported as liquids or solids, they must be converted to gas (often through heat or reduced pressure) for the actual application process. Hence, selecting the gaseous form reflects their primary application method in controlling pest infestations.