Technical Abstract: Commercially available, microbial insecticides, are formulated either as sprayable liquids or wettable powders. Little research and development has focused on the possible use of dust formulations of microbial pesticides. Dust formulations of microbial insecticides may: recover more activity during production; increase shelf stability; disperse more uniformly over plants; and, provide more sunlight-UV protection. In this note we evaluated the simulated sunlight-ultraviolet (SUV) stability of dust formulations of inclusion bodies (PIB) of the singly-enveloped nucleopolyhedrosis virus of Helicoverpa/Heliothis (HzSNPV). Less than 5% of the original viral activity was still present after exposure of only PIB to SUV. Although individually adding a UV-protectant (carbon or Shade**TM) or an inert dust (talc) increased the SUV-persistence of PIB, they individually did not give the same level of protection as shielded PIB. Dust formulations of PIB + talc + a UV-protectant, however, were as active as PIB shielded from SUV.