Loire Valley Nature: Sweat Bees

Bees are generally easy to identify to genus level using a simple wing venation based key (such as the FSC Aidgap Key to Bees, Ants and Wasps) if you have a specimen. They are not so easy to identify from photos or to species level.

Halictus is a very large genus of bees, with 30 species occuring in France. They are ground nesting, and sometimes social, forming colonies, sometimes nesting individually. Nests are about 5mm in diameter, surrounded by a little pile of excavated soil. They are small-medium sized bees with dark bodies and pale bands on their abdomen. Identification to species level from photographs is usually very difficult and requires expert opinion. Many species are so similiar in appearance that even the experts on forums such as HymIS and BWARS often cannot tell them apart without examining actual specimens. They are also very difficult to tell from Lasioglossum spp (the key difference is the position of the abdominal bands, which are at the top of each segment in Halictus and at the bottom in Lasioglossum).

Halictus rubicundus, female (identified by Christian Schmid-Egger
on HymIS) photographed in March.

Halictus have more cylindrical abdomens than Andrena. They fly from early spring to mid-summer.

H. rubicundus has clear yellow hind tibiae and white abdominal bands. It is common and widespread.

Photographed by Loire Valley Nature:
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Halictus sp on Early Spider Orchid Ophrys sphegodes. Curiously this is a female bee (note the slit in the end of the abdomen), so sexual deception by the orchid is presumably not the lure.

Female Halictus sp on Early Spider Orchid O. sphegodes. The bee was very agitated and attempting to get into the orchid flower every which way. The flower is so newly opened that it is still upside down (they right themselves in time after opening).