The need for detailed investigations into the life-history and morphology of Phaedon cochleariæ F. first became apparent during field experiments which were designed to elucidate the problem of the control of this beetle on cultivated watercress in South Wales and Monmouthshire. Reference to literature revealed that our knowledge hitherto concerning this species was very meagre, and that even the information available differed in important respects from the experience gained during these preliminary studies on its control.
In the course of these investigations, the life-cycle of the beetle, as it occurs on watercress, has been followed out together with its hibernation habits and the duration of the various larval and pupal stages. A perusal of accounts of previous work on this beetle showed that only two generations of adults have been described, but in the present work it was found that actually there are three generations produced in the year. In addition, a detailed study has been made of both the external and internal anatomy of all stages in the life-cycle.