I've found Ultricularia gibba (bladderwort), a aquatic carnivorous plant, is very effective at keeping mosquitoes from breeding in aquaculture tubs, plant pot saucers, and other small containers of water where mosquitoes normally like to lay their egg rafts. Bladderwort's bladder trap catch and eat mosquito larvae. Mosquitoes can apparently detect and refuse to lay their eggs in water where Ultricularia is growing. It is especially good for locations where predators such as frogs keep eating your mosquito fish and rosy red minnows. U. gibba is native throughout the world from the tropics to as far north as Canada.
He was giving me directions and I was powerless to resist. I cannot resist this tiny ad: