Abstract: A molded non-layered unitary article (serving as a larvicide carrier) is formed solely from a substantially homogeneous mixture consisting of cork particles and a molding- type of plaster into which a larvicidal micro-organism, such as B.t.i., has been added. The article may be dispensed conveniently, on to either small or large bodies of water, without regard for its orientation relative to the body of water. The article has a specific gravity of less than 1.0 and floats freely on the surface of the water, but if desired, may have a restrained-floating application. A sustained release of the larvicidal micro-organism is assured for effective mosquito control. All of the ingredients are found in nature, are bio-degradable, and are non-toxic to non-target organisms; hence will not adversely affect the environment. In a preferred embodiment, the article is substantially-toroidal and slightly-tapered and is provided with a central opening therein.