Scientifically, pitcher plants are called Nepenthes, though most people call them monkey cups. This, of course, doesn't mean that a monkey can be eaten by a plant. Probably such name appeared when people saw monkeys drinking rainwater from these plants.
The greatest variety of pitcher plants can be found within the Malay Archipelago. There are several locations in Malaysia which possess the highest density of different kinds—the Borneo montane rain forests, Gunung Mulu National Park, and Kinabalu National Park. More than 15 kinds of Nepenthes can be found there.
Nepenthes faizaliana is endemic to the limestone peaks of Mulu. If one wants to find them, the best option would be to follow the the Pinnacles Trail on Mount Api.
Nepenthes Rajah is endemic to Sabah region and can be spotted in Kinabalu National Park. It is the biggest pitcher plant in the world. Its trap usually holds up to 2 liters of liquid, but some exceptional plants can reach a volume of up to 2-3 litres of water. The King of Nepenthes traps not only insects, but also small animals like rats, shrews, lizards, and birds.
Pitcher plants grow through the year, but they are more active and produce more leaves during warmer and drier months—between March and October.