The Diesel Bug is a consortium of organisms which live at the fuel water interface. They live in the water phase whilst feeding on the fuel. Of all the organisms in this consortium, H res is the most recognisable and also damaging component of ‘sludge’. This fungus is the main culprit in instances of filter blockage & tank corrosion when left unchecked. The rest of the consortium includes bacteria and other types of fungi, particularly some yeasts which can also cause fuel system problems.