Lasioglossum zephyrus is a sweat bee of the family Halictidae, found in the U.S. and Canada.

[4] For instance, Lasioglossum zephyrus, as well as another species of this family of bees, Halictidae, Halictus ligatus, are known for their characteristic primitively eusocial behavior.

[4] Lasioglossum zephyrus is characterized by its dark green metallic color, reddish abdomen, and a hairier face than most other species.

[6] Since the castes vary along a spectrum, there is no definite way to distinguish a worker from a queen based on appearance alone.

[7] However, queens can be identified by their behavior, pushing subordinates down in the nest and nudging them to inhibit their reproduction.

Workers use their mandibles to loosen the soil, then carry it a short distance to be picked up by another bee.

Females excavate cells and line them with a liquid produced in their enlarged Dufour's glands and secreted from the apex of the abdomen.

[9] L. zephyrus colonies have a high mortality rate, especially when inhabited by a solitary bee lacking guards.

[9] This type of hierarchy is very different from other species of bees, such as Lasioglossum hemichalceum, which is characterized by its egalitarian behavior and lack of aggression.

[8] The tendency to display these behaviors is not influenced by the genetic relatedness of the subordinate bee, but it does decrease with time.

As adults, Lasioglossum zephyrus females become either mated egg-layers or workers who forage, guard, and make cells.

[9] In a typical Lasioglossum zephyrus colony, the oldest females tend to be mated queens.

[7][14][15] Early in the spring, the males are solitary or clustered in small groups, but by late summer they gather in swarms of thousands of bees.

[15] While foraging, L. zephyrus searches for flowers, sometimes even forcing them open in order to get first access to the pollen.

Mating tends to take place near the nest's entrance, where the males typically fly.

Males will approach and occasionally grasp bees of other species, but no heterospecific matings have been documented.

Most of the males' attempts at mating were met with resistance, but the females tend to remain relatively motionless during copulation.

[18] In Hymenoptera species, like Lasioglossum zephyrus, females are diploid and males are typically haploid, in a system called haplodiploidy.

They also tend to produce more eggs of better quality, and greater size increases the chance that a female survives the winter.

[16] Lasioglossum zephyrus has been parasitized by diverse organisms including bacteria, fungi, protozoa, and other species of hymenoptera.

Nematodes have been found in the abdominal cavities of L. zephyrus females, and have led to a reduction in ovarian development.

Guard bees are often responsible for the protection of the nest and will send one member to attack while the others block the entrance with their abdomens.

[7] The mutillid Pseudomethoca frigida is also a parasitoid, and known to engage in aggressive fights with female L. zephyrus.