A simple, readily transportable apparatus for maintenance of black fly larvae in the laboratory is proposed as an alternative to a full-scale rearing system. This compact apparatus of the compressed-air type can maintain dense populations of black fly larvae without time-consuming manipulation. Large numbers of Simulium venustum Say complex, Simulium decorum Walker, and Prosimulium mixtum Syme & Davies group larvae (> 1,200 larvae per liter) were maintained successfully at low temperature in our laboratories for 3 – 5 mo. Mortality rates for mid- to late instars of each of the three species were <5%. Large areas of removable substrate allow easy access to larvae. This system can be used in the field to transport larvae to the laboratory, where they can be maintained or reared to the adult stage.