Generalist. Widespread. Solitary.
Name: ‘The Green Sweat Bee’ (there are several)
Family: Halicitinae (with: other sweat bees, alkali bees)
States: Most likely all except Hawaii and Alaska
Agapostemon texanus belongs to one of North America’s most striking genera – all Agapostemon males and females have beautiful, metallic blue/green coloration. Males and females of Agapostemon species look very different (a phenomena called sexual dimorphism). Male abdomens are yellow-and-black/brown striped while female abdomens are consistently metallic and blue-green.
Of all the Agapostemon, A. texanus is the most widespread, appearing from Costa Rica to Southern Canada. In the US, it is most common west of the Mississippi River. A. texanus has two generations a year, with mostly males active in the early fall and mostly females hibernating through the winter and active in spring and early summer (this split is due to a unique system called haplodiploidy).
Female A. texanus are strictly solitary, though females of closely-related species (like A. radiatus) have been found to make all their nests together in one area (called an aggregation) or potentially even use singular nests communally (A. nastus).
A. texanus nest in the soil, creating long tunnels by digging. Females search for dark spots under pebbles or leaves to construct the entrance to the nests, making nests hard to spot by parasites. Females leave their nest open during the day as they forage on a variety of flowers (A. texanus are generalists) before closing the nest entrance in the late afternoon/early evening by pushing soil up from inside the main tunnel to close the door for the night. High security area!
Nests tunnels have been found up to 150 cms deep (nearly five feet!).
Sources and Further Reading (first is freely available and has a great drawing of an A. texanus nest!):
Roberts, R (1973). Bees of Northwestern America: Agapostemon (Hymenoptera: Halictidae). Technical Bulletin of the Agricultural Experiment Station at Oregon State University, 125: 1-23.
Eickwort, G (1981). Aspects of the Nesting Biology of Five Nearctic Species of Agapostemon (Hymenoptera: Halictidae). Journal of the Kansas Entomological Society, 54: 337-51.
Porter, C (1983). Ecological Notes on Lower Rio Grande Valley Augochloropsis and Agapostemon (Hymenoptera: Halictidae). The Florida Entomologist, 66: 344-53.
Waddington, K (1979). Flight patterns of Three Species of Sweat Bees (Halictidae) Foraging at Convolvulus arvensis. Journal of the Kansas Entomological Society, 52: 751-8.