Augochlora pura

Augochlora pura

''Augochlora pura'' is a solitary sweat bee found primarily in the Eastern United States. It is known for its bright green color and its tendency to forage on a variety of plants. Inhabiting rotting logs, this bee can produce up to three generations per year. Both males and females have been observed licking sweat from human skin, most likely seeking salt
Pure Green Augochlora These bees are referred to as "sweat bees" because they like to lick sweat from human skin, most likely seeking salt. Electrolytes such as sodium are important for nerve and muscle function, in addition to a variety of other life processes. So, it appears that sweat bees imbibe human sweat in order to help them maintain homeostasis. Interestingly, as you can see in these photos, these bees are cobbling their nests together using galleries in the wood that were probably made by other insects. Within these galleries, the female bees will leave cakes made of pollen, nectar, and spit, which will soon be food for her offspring. It's thought that her saliva is added to the cakes because it has antiseptic qualities that help keep the food fresh and add extra protection to the eggs. After a brief interlude with a mate, she will lay eggs on the pollen/nectar balls. The nests are lined with a thin, impermeable membrane that she produces from glands in her body. The nests need this added protection because there are many predators that would gladly devour her offspring. When the larvae hatch, they consume the nutritious cakes. Once larval development is complete, they will pupate, and then emerge later as adults.  Augochlora pura,Fall,Geotagged,Pure Green Augochlora,United States,bee

Appearance

Both males and females are approximately 8 mm long. Their entire bodies are a shiny, bright green, in contrast to the primitively eusocial American sweat bee ''Lasioglossum zephyrum which is primarily metallic brown'', but sometimes with a coppery sheen. Male ''Augochlora pura'' tend to have darker mandibles and may be slightly more bluish than females, but otherwise, males and females are similar.
Pure Green Augochlora I originally spotted these beautiful bees cobbling nests in a rotting stump during October. I went back to the location a couple weeks later to check on them, and found that their stump had been completely dug up and pulverized. There was bear sign nearby, and so I'm guessing that a bear dug up the stump to feast on the treats hidden in there as there were lots of ants, bees, and larvae in the rotting stump. I did see a couple sweat bees still in their cells though, while a couple others aimlessly roamed the remains. I gathered the remaining chunks of stump and piled them back on top of the bees' galleries in an attempt to give them some protection during the cold winter. 
 Augochlora,Augochlora pura,Fall,Geotagged,Pure Green Augochlora,United States,bee,green bee

Naming

Inside rotten logs, ''A. pura'' has been seen to associate with nests of another bee species, ''Lasioglossum coeruleum''.

''A. pura'' utilize the powdered wood produced by passalid beetles when constructing their nests.

Many ''A. pura'' found dead in the spring are covered with the fungus ''Fusarium''. It is unclear whether the fungus was actually the cause of death.

Parasitic nematodes of the species ''Aduncospiculum halicti'' have been discovered in the Dufour's gland and genital tract of both males and females.
Pure Green Augochlora Beautiful, shiny green bee, covered in pollen!  

These bees are referred to as "sweat bees" because they like to lick sweat from human skin, most likely seeking salt. Electrolytes such as sodium are important for nerve and muscle function, in addition to a variety of other life processes. So, it appears that sweat bees imbibe human sweat in order to help them maintain homeostasis.

Spotted in a rural garden. Augochlora pura,Geotagged,Pure Green Augochlora,Spring,United States,bee,green bee,sweat bee

Distribution

''A. pura'' is found mainly in the eastern United States. It ranges from Maine through Minnesota south through Texas and Florida. ''A. pura'' has been documented as far north as Quebec. Its active season is February through November, with the longer seasons in the more southern states. ''A. pura'' builds its nests in rotting wood in forests and even wood piles in suburbia. It spends most of its time near its nests, but also visits nearby brush and pastures. According to a study on the bottomland hardwood forest of the southeastern United States, ''A. pura'' accounted for about 91% of bees collected in the area.
Augochlora pura Gold sweat bee(?) on Jewelweed at the edge of a dense mixed forest. Augochlora pura maybe?  Augochlora pura,Geotagged,Summer,United States

Behavior

''Augochlora pura'' has a flight season from early April through September, but nests are active only from early May to early August. Unlike other halictids, ''A. pura'' does not take flight in response to warm days later in the fall. There are two to three generations per year in nature, as limited by the seasons, but bees in the laboratory have been shown to produce at least six generations per year. There is no reason to believe these generations would not continue indefinitely. In nature, females become active in August and September, mate, and remain in a state of ovarian diapause on moist soil beneath rotting logs. In contrast, all males die in the fall. Overwintered females found new nests in April. Their offspring emerge in June, and proceed to found nests of their own by the end of the month. Males tend to emerge from the first cells built, and females emerge shortly thereafter. Males in the laboratory live on average about 14.88 days.As solitary bees, ''A. pura'' females do not remain in their mother's nest if she is alive. However, there may be times in which ''A. pura'' females group together. When the mother is old or deceased, multiple young females may live as a group. Multiple females have also been seen huddled together while overwintering. There is no worker caste, and reproductive females are not cooperative. Bees attempting to enter a nest that does not belong to them will be promptly attacked. Mothers have even been observed to attack their own offspring. If nests meet by chance, a wall is quickly constructed between them. Males return to the same sleeping places each night, and may sleep in groups of up to six males, but only if sleeping places are limited. In this case, all males sleeping together face the same direction. Males enter vacant nests and attack any other males attempting to enter.''Augochlora pura'' mates while visiting flowers. All, or nearly all, females mate. Males fly in swarms and hover over flowers. They fly from flower to flower and feed, and land on any similarly sized insect on a flower. In fact, they even pounce on black dots on paper. When a male finds a receptive female, he mates with her for from three seconds through two minutes. Instead of pursuing females in the air, ''A. pura'' males wait for them to land on flowers. As in ''Lasioglossum zephyrum'', the odors of ''A. pura'' females function as aphrodisiacs. Males have been observed to stack themselves on top of a copulating male, attempting to mate with that one female. ''Augochlora pura'' males have been observed to stroke the female's head with their antennae before and during copulation. During copulation, the male will release his grasp and remain connected only by his genitalia. Females may attempt to crawl or bite the male's metastoma. Copulation in the field lasts for approximately 28.5 seconds. Males have not been shown to have a preference for either young or old females.''Augochlora pura'' forages on a variety of flowers, including more inconspicuous flowers like walnut. They have been observed visiting over 40 distinct species. In the laboratory, ''A. pura'' even foraged for nectar, pollen, or both at foreign flowers not found near their natural habitat. A female collect pollen from up to ten flowers to provision a single cell, and these are often from different species. Males exhibit patrolling behavior. They fly between specific flowers, and maintain this route continuously with only short rests. They fly so quickly that they may be difficult to follow visually.
Pure Green Augochlora Nest I found this curious little sawdust structure in a hole on a snag that was still standing in a coniferous forest. There was a lot of pileated woodpecker holes in the snag, so it must have been full of tasty delights, including this Pure Green Augochlora nest!  It was a very fragile structure, so I didn't disturb it, but I noticed holes on the ends for the different cells and a yellow substance in them, which I think were eggs.  

Note - the slug photobombed my shot. Augochlora,Augochlora pura,Geotagged,Pure Green Augochlora,Spring,United States,bee nest,nest

Habitat

''A. pura'' is found mainly in the eastern United States. It ranges from Maine through Minnesota south through Texas and Florida. ''A. pura'' has been documented as far north as Quebec. Its active season is February through November, with the longer seasons in the more southern states. ''A. pura'' builds its nests in rotting wood in forests and even wood piles in suburbia. It spends most of its time near its nests, but also visits nearby brush and pastures. According to a study on the bottomland hardwood forest of the southeastern United States, ''A. pura'' accounted for about 91% of bees collected in the area.

References:

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Taxonomy
KingdomAnimalia
DivisionArthropoda
ClassInsecta
OrderHymenoptera
FamilyHalictidae
GenusAugochlora
SpeciesA. pura