Why do I need a Bombilla? Yerba Mate is traditionally served with a bamboo or metal straw from a shared hollowed out gourd. This drinking straw is called a bombilla in Latin American Spanish and a bomba in Portuguese. The bombilla (also known as a tea straw, filter straw, or bomba) acts as a strainer in addition to a drinking straw. The submerged end has small slots that allow your mate tea infusion to pass through, but blocks the loose yerba mate herb that fills the mate gourd.