Bumblebee (Bombus terrestris) on turtlehead (Chelone glabra) flower. These flowers have a hinged door preventing small insects from gaining access to the corolla and its nectar. Bumblebees are large and strong enough to pull open the hinged door.
Bumblebee (Bombus impatiens) on apple blossom in my yard
Augochlora pura, a small solitary sweat bee (Halictidae).
Exaerete sp. and Eufriesea ornata males attracted to a scent bait in Costa Rica.
Agapostemon sericeus, a small male communal (primitively social) sweat bee (Halictidae). (Females are entirely green)
Euglossa sp. male with an orchid pollinia attached to its dorsal thorax.