Halictidae is the second-largest family of bees with nearly 4,500 species. They are commonly called sweat bees, as they are often attracted to perspiration. Halictid species are an extremely diverse group that can vary greatly in appearance. These bees occur all over the world and are found on every continent except Antarctica. Usually dark-colored and often metallic, halictids are found in various sizes, colors and patterns. Several species are all or partly green and a few are red, purple, or blue. A number of them have yellow markings, especially the males, which commonly have yellow faces, a pattern widespread among the various families of bees. The family is one of many with short tongues and is best distinguished by the arcuate basal vein found on the wing. Females in this family tend to be larger than the males. They are the group for which the term 'eusocial' was first coined by entomologist, Suzanne Batra.

The Colletidae are a family of bees, and are often referred to collectively as plasterer bees or polyester bees, due to the method of smoothing the walls of their nest cells with secretions applied with their mouthparts; these secretions dry into a cellophane-like lining. The five subfamilies, 54 genera, and over 2000 species are all evidently solitary, though many nest in aggregations. Two of the subfamilies, Euryglossinae and Hylaeinae, lack the external pollen-carrying apparatus that otherwise characterizes most bees, and instead carry the pollen in their crops. These groups, and most genera in this family, have liquid or semiliquid pollen masses on which the larvae develop.