The Giant Leaf Frog or Monkey Frog (Phyllomedusa bicolor) is a nocturnal hylid frog that is native to the tropical regions of South America with a broad range extending from Bolivia, Eastern Peru, Northern Brazil, Venezuela, and Colombia to the Guianas. The skin of the frog produces a poisonous waxy secretion that is known to contain dermorphines-like peptides that are thought to activate opoid receptors. The Matses easily locate and capture the frog by listening for the distinctive mating-call of the male. Curiously, Phyllomedusa bicolor loses its capacity to produce venom when reared in captivity.