What characteristic is common to all pesticides labeled as fumigants?

Fumigants are unique among pesticides because they undergo a transformation into gases when applied. This is a critical characteristic that distinguishes them from other types of pesticides. When a fumigant is released, it volatilizes, meaning it changes from a liquid or solid state into gas, which can penetrate spaces thoroughly, including soil, buildings, and stored goods. This gaseous state allows fumigants to effectively target pests that may be hiding in crevices or inaccessible locations where other forms of pesticides may not reach.

In contrast, fumigants are not typically liquids in their final application form, nor are they generally solids; they must transition into a gaseous phase to perform their function effectively. Furthermore, while some fumigants can be used indoors, they are not exclusively designed for indoor use, as many are also employed in agricultural settings for soil treatment or stored product pest control. Thus, the defining feature lies in their ability to volatilize and create a gas, which ensures an extensive and effective distribution for pest control.