Milwaukee mining bee

Milwaukee mining bee, often called Milwaukee miner bee, is an early season, northern, mining bee. It occurs in the United States from Maine to New York, west to Washington, south along the Appalachian Mountains to North Carolina, and south along the western interior mountain ranges to Arizona. It also occurs throughout Canada and in Alaska. It is common in Minnesota. It appears from April through June. It collects pollen from a variety of unrelated plants.

Females are ⅜″ to ½″ (9 to 13 mm) in length. Males are a little smaller, 5⁄16″ to ½″ (8 to 12 mm) in length. The body is black and is partially covered with long, erect, hairs. The hairs are usually yellowish red (fox-colored), sometimes yellowish brown.

The head is entirely black, but there are often some fox-colored or yellowish-brown hairs on the face and at the rear of the top of the head (vertex). There are two large compound eyes on the sides of the head and three simple eyes (ocelli) in a triangle on top of the head. The compound eyes are distinctly vertical. The inner margins are straight up and down and close to parallel. Next to the inner margin of each compound eye there is a slight depression (fovea) out of which emerges a dense band of pale hairs. The foveae are large and shallow. The tongue is short and pointed. The antennae of the male have 11 segments (flagellomeres) beyond the scape and pedicel. The female antennae have 10 flagellomeres. There are two grooves (subantennal sutures) below the base of each antenna, though these cannot be seen without careful handling and possibly also a microscope.

The thorax is black and is densely covered with long, erect, fox-colored or yellowish-brown hairs.

The female has six abdominal segments, the male has seven. There are two geographically distinct color forms of the female. On the western form, abdominal segments 1 through 4 or 5 are densely covered with long, erect, fox-colored or yellowish-brown hairs. On the eastern form, only segments 1 and 2 have those hairs. On the male, only segment 1 and the front of segment 2, or segments 1 and 2 and the front of segment 3, have those hairs.

The forewings are mostly clear but moderately darkened toward the tip. The marginal cell is relatively long and is pointed (narrowly rounded) at the tip. There are three submarginal cells. The second submarginal cell is much shorter than the first and third. The basal vein is nearly straight. The broad lobe at the base of the hindwing (jugal lobe) is longer than the narrow cell adjacent to it (submedian cell).

On the female, the pollen-collecting hairs (scopa) on the hind legs are long and dark.

Female: ⅜″ to ½″ (9 to 13 mm)

Male: 5⁄16″ to ½″ (8 to 12 mm)

Prairies, weedy fields

One generation per year: April through June

The female creates a vertical tunnel in the ground with side tunnels branching off. Each side tunnel is a cell that contains a single egg and is provisioned with a ball of pollen mixed with nectar.

Pollen mixed with nectar

Flower pollen of a wide variety of plants

Sources

4, 29, 30, 82, 83.

LaBerge, W. E. (1980). A Revision of the Bees of the Genus Andrena of the Western Hemisphere. Part X. Subgenus Andrena. Transactions of the American Entomological Society (1890-), 106(4), 395–525. http://www.jstor.org/stable/25078273

Common

Andrena milwaukeensis

I was fortunate to get a few pics of this Milwaukee mining bee, Andrena milwaukeensis. Photos were taken May 15, 2023 near Barnes Prairie, Racine County, WI.

Andrena milwaukeensis
USGS Bee Inventory and Monitoring Lab

Miner Bee (Andrenidae: Andrena milwaukeensis) Female
Carl Barrentine

Miner Bee (Andrena milwaukeensis) Female, Close-up
Carl Barrentine

Babette Kis
5/15/2023

Location: Barnes Prairie, Racine Co., WI.

I was fortunate to get a few pics of this Milwaukee mining bee, Andrena milwaukeensis. Photos were taken May 15, 2023 near Barnes Prairie, Racine County, WI.