Field Notes: Lasioglossum Sweat Bee Nesting Site, South Carolina

© Clay Bolt / www.claybolt.com

A small Lasioglossum sweat bee outside the entrance of its nest. © Clay Bolt / www.claybolt.com

Last summer, as I walked up my gravel driveway to get the mail I noticed a flurry of activity around several very tiny holes on the hard-packed, clay embankment. I had seen the holes before, but assumed that they belonged to ants. In fact, I had photographed several Big-headed Ants (Pheidole sp) in the same spot during the summer before. However, to my delight, after close inspection, I noticed that the insects that I had noticed were actually Lasioglossum sweat bees.

© Clay Bolt / www.claybolt.com

A small Lasioglossum sweat bee approaches its nest. © Clay Bolt / www.claybolt.com

I have been eagerly awaiting their return this spring and today was the first day when activity around the small nesting chambers was in full-swing. Sweat bees are not social nesters in the same fashion of honey bees. Instead, a single entrance (that is often guarded by an individual), which leads to several separate chambers in which one of may females will construct a ball of pollen in which to lay an egg. You might describe it as an apartment complex for bees, except that the bees aren’t utilizing the nests for a living space.

© Clay Bolt / www.claybolt.com

Although the vast majority of native North American bees are solitary, some species, such as this Lasioglossum Bee, live in communal nests with one central opening that leads to several nesting chambers that are used by a single female. Individuals will take turns playing guard. This small nest opening is barely larger than the head of a pin. © Clay Bolt / www.claybolt.com

Interestingly enough, I also noticed another very interesting visitor to the nesting site. A Bee Fly (Bombylius sp) was patrolling the nest entrances in search of a place to lay her eggs.  This species parasitizes ground nesting sweat bees. Surprisingly, the bees paid little to no attention to the Bee Fly as she went about her way. During this my observation time I also noticed a female Sphecodes bee, which is a sub-species of Lasioglossum that is a kleptoparasitic species that takes advantage of the hard work of other sweat bees. Rather than collecting her own pollen to feed her young, a female Sphecodes lays her eggs in the nest of another Lasioglossum species which does. Once the Sphecodes young has hatched, it will consume the food source, ultimately starving out the young of its host-species. Lovely! Female Sphecodes can be recognized by their bright red abdomens.

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A Bee Fly (Bombylius sp) patrolling the Lasioglossum nest entrances in search of sites for her to lay her eggs. The small mound on the bottom left is a sweat bee nest. © Clay Bolt / www.claybolt.com

© Clay Bolt / www.claybolt.com

A Bee Fly (Bombylius sp) flies toward the opening of a Lasioglossum nest entrance to lay her eggs. © Clay Bolt / www.claybolt.com

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