Abstract: A device for combating the proliferation of aquatic larvae in containers likely to hold stagnant water, the containers (1) including a wall (2) defining a cavity (3) and an open hole (4), and including an element (10) whose shape is designed to completely or partially conform to that of the wall (2) of the cavity and to seal the hole, the element being produced from a porous material permeable to air and to water, including a rubber granulate and a synthetic binder. The device made from porous material occupies the opening of the tank which can therefore no longer be freely accessed by mosquitoes. A method implementing such a device is also described.