This will depend on some factors. For example in a warmer climate in the middle of summer, the process can take up to a month to actually happen. It will also depend on the species of butterfly. On average the Monarch butterfly, one of the most identifiable species, can take up to 14 days to emerge from the cocoon. However, the Painted Lady, which is one of the most common species and one that is often included in the butterfly kits, takes only seven to 10 days to emerge.