Many mealybug species, including Planococcus spp. and Pseudococcus spp., are of economic importance as pests of agricultural crops and ornamental plants. They are also used as models in scientific research with different objectives due to their particular biological characteristics and also because they are easy to rear in the laboratory. Traditionally, their rearing is carried out on sprouted potatoes, under dark and controlled conditions of temperature and relative humidity, in order to avoid the production of solanine when the potatoes are exposed to light, as this glycoalkaloid is toxic to the insects. However, it has been questioned whether the rearing in the dark for several generations could affect the behavioural responses and biological parameters of the mealybugs, and thus the results obtained in experiments in which these mealybugs are used. In this study, we tested this hypothesis by comparing the development, fecundity and fertility of mealybugs reared in two different photoperiod conditions: 00L:24E and 12L:12E.