This paper combines some of the results from three studies that explain the system by which the gut of Phlebotomus papatasi is maintained bacteria free. This system includes an antibacterial factor in the crop (diverticulum) and feeding behaviour which determines selective routing of meals. When feeding by piercing animal skin or plant tissue, in a ‘blood feeding’ mode, the uncontaminated meals of both sources enter the midgut directly. Free-solution sugar-meals which may contain contaminants, enter the crop where they mix with the antibacterial agent. Feeding on plants is also described.
