What type of duster is typically used for applying small quantities of dust?

The hand bellows and bulb duster is specifically designed for applying small quantities of dust in a controlled manner. This tool allows the operator to dispense the dust with precision, making it effective for targeting specific areas, such as cracks and crevices where pests may hide. The manual operation of the duster helps achieve a fine, even application, which is important for both effectiveness and avoiding oversaturation.

In contrast, the other options are not ideal for this purpose. A hydraulic sprayer is designed for applying liquids in larger volumes, making it less suitable for dust applications. A backpack sprayer also focuses on liquid applications, which would not provide the same precision needed for dust. Lastly, a cold-fog generator produces aerosolized droplets for covering larger areas and is inappropriate for small, targeted applications of dust. Hence, the hand bellows and bulb duster stands out as the best tool for the task described.