Lasioglossum zephyrus
Lasioglossum zephyrus is a sweat bee of the family Halictidae, found in the U.S. and Canada. It appears in the literature primarily under the misspelling "zephyrum". It is considered a primitively eusocial bee (meaning that they do not have a permanent division of labor within colonies), although it may be facultatively solitary (i.e., displaying both solitary and eusocial behaviors). The species nests in burrows in the soil. Taxonomy and phylogeny The order Hymenoptera contains more eusocial species than any other order. Eusociality has many origins and is present in many degrees within Hymenoptera, with L. zephyrus being one of the more primitive examples. The genus Lasioglossum is predominantly eusocial, but has a high level of variation in sociality. 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. This unique type of eusociality gives insight about the evolutionary background of eusociality of these species. Six species within this genus have reverted to solitary life, social polymorphism, or parasitism. Description and identification Lasioglossum zephyrus is characterized by its dark green metallic color, reddish abdomen, and a hairier face than most other species. Males are 6 to 7 millimeters long, slightly larger than females. Males are distinguished from females by their brighter green color and redder abdomens. Since the castes vary along a spectrum, there is no definite way to distinguish a worker from a queen based on appearance alone. However, queens can be identified by their behavior, pushing subordinates down in the nest and nudging them to inhibit their reproduction. Distribution and habitat L. zephyrus has been found throughout the United States, in the months of March through October. Nests are usually constructed in April along the south facing edges of streams, and are clustered in aggregations of up to 1,000 nests. It nests in burrows that are typically constructed by young females. However, older females may also contribute to burrowing if their nests have been destroyed. These females excavate primarily at night, but activity has been reported throughout the day. Workers use their mandibles to loosen the soil, then carry it a short distance to be picked up by another bee. This soil is ultimately smoothed over the walls or used to fill evacuated old burrows. Females excavate cells and line them with a liquid produced in their enlarged Dufour's glands and secreted from the apex of the abdomen. Colony cycle Lasioglossum zephyrus nests consist of less than 20 individuals. During the spring, around April, new nests are established by one or more females. Some of these nest may never gain more members, and the female will remain solitary. If they do expand, the colony will reach its maximum size of 10–20 around August. Growth of the colony is gradual throughout the summer. Inseminated young queens overwinter in their nests so that the cycle may be repeated. However, overwintered queens are likely to die early on in the summer. After the death of an old