Fly traps that do not require toxic chemicals and that can un-intrusively be present in public areas. An example trap includes a housing to contain a solution and including opening(s) for ingress of flies, a conduit or nozzle, a pump to cause solution to flow via the conduit/nozzle and along the inner surface of the housing to capture flies, and a timer to activate the pump. Another example trap includes a gathering vessel, conduit coupled to the vessel and to be submerged in a fluid trap, a vacuum to remove air from the fluid trap, and a timing device to activate the vacuum. Another example trap includes an outer wall to contain a solution, an inner wall extending into the solution, an air pump and conduit(s) to form bubbles in the solution that rise in a space between the outer and inner walls and cascade down the inner wall.