Per page 16 of the label, you can apply Talak 7.9% F Insecticide in livestock housing areas, kennels, etc., to kill any adult fungus gnats. Please read and follow the label instructions to ensure proper application.
Talak 7.9% F Insecticide is your residual product. You will need to add the ExciteR Insecticide or Stryker Multi-Use Insecticide for a fast knockdown.