How do I take care of catepillars in a contained environment? Don't feed them anything other than the plants listed for their species.. They will not survive. Don't provide them with water. They get all the moisture they need from the leaves they eat and could drown. Don't put their home in direct sunlight. It gets hot in there! Do keep them supplied with lots of fresh leaves. They eat a LOT before they form their pupa. Do keep extra leaves in the refrigerator to stay fresh. Do be patient! They can take 10 to 14 days or more to emerge from their pupa. Do have fun watching them grow!