Adults will feed from a variety of small flowers such as Lantana. They are also known to feed on rotting fruits.
The genus Adelpha is Greek for sister. The origin of the specie fessonia is currently unknown.
The Mexican Sister prefers to stay in the vicinity of forest areas so they are usually found along the forest edge or in clearings within the forest.
When they are not feeding the males sit in an open location waiting for a female to pass by. After mating the female lays individual eggs on the leaves of the host plant. The caterpillar feeds on the host plant until it forms its chrysalis.
In the northern part of their range there are multiple generations making it possible to find adults March-November while in the southern part it is believed they can be found year round.
While it is considered native to Texas the Mexican Sister is really only found in the southernmost tip of Texas and can actually be quite hard to find in those areas during certain years.
