The small white will readily lay eggs on both cultivated and wild members of the cabbage family, such as charlock ("Sinapis arvensis") and hedge mustard ("Sisymbrium officinale"). "P. rapae" is known to lay eggs singularly on the host plant. The egg is characterized by a yellowish color and 12 longitudinal ridges. The egg production peaks about a week after adulthood in lab and the female can live up to 3 weeks. Females tend to lay fewer eggs on plants in clumps than on isolated plants. It has been suggested that isothiocyanate compounds in the family Brassicaceae may have been evolved to reduce herbivory by caterpillars of the small white. However, this suggestion is not generally accepted because the small white has later been shown to be immune to the isothiocyanate forming reaction due to a specific biochemical adaptation. In contrast, the small white and relatives seem to have evolved as a consequence of this biochemical adaptation to the isothiocyanate-forming glucosinolates.