Descriptions of several Hydroecia larvae have appeared in this magazine at various times, but as they were instance when the insects were infesting cultivated plants, the following notes are submitted to show their life history when found in more natural environments, and to assist the student in obtainin sufficient material in some of the species for comparative work. From the paucity of examples in collections and from the close relationship existing between most of the species, it is necessary to resort to breeding, or at least to have such a knowledge of their early habits as to secure extended series, before a very correct idea may be had of the representatives of this genus.