Boron, a known pesticide can be impregnated into the paper fibers of cellulose insulation at certain levels to achieve a mechanical kill factor for self-grooming insects such as ants, cockroaches, termites, and more. The addition of insulation into the attic and walls of a structure can provide control of common pests in addition to known insulation benefits such a robust thermal envelope and acoustic noise-canceling properties. The EPA regulates this type of general-use pesticide within the United States allowing it to only be sold and installed by licensed pest management professionals as part of an integrated pest management program. Simply adding Boron or an EPA-registered pesticide to an insulation does not qualify it as a pesticide. The dosage and method must be carefully controlled and monitored.
Read more, here.