The “sweat bees.” Members of this large group of bees are active throughout the year, and are generally black, or metallic green or blue. Halictids are best known for dazzling array of social structures, ranging from solitary nests led by a single female to eusociality with division of labor among queens and many female workers. Many of them nest in the ground, while others excavate nests in rotting logs. The diverse and enigmatic genus Sphecodes is cleptoparastic.