Giant sweat bee

Description

Giant sweat bee is a medium-sized to large, dark, solitary, ground-nesting bee. It occurs in the southern two-thirds of the United States and in northern Mexico. There are two recognized subspecies of giant sweat bee. Dieunomia heteropoda ssp. kirbii, the southern subspecies, is a large bee, and is the source of the common name. Dieunomia heteropoda ssp. heteropoda), the northern subspecies, is a medium-sized bee. Only the northern subspecies occurs in Minnesota. It was first collected in Minnesota in 1824 in Scott County.

The male is ⅝″ (17 mm) in length.

The head is black and shiny. The face is rounded. There is a single line-like groove extending downward from the base of each antenna (subantennal suture). The tongue is short. The antennae on the female have 12 segments, on the male they have 13 segments. The last antennal segment on the male is broad and flattened.

The thorax is shiny black, coarsely punctured (pitted), and densely covered with hairs.

The abdomen is black, shiny, and densely punctured. At the end of each abdominal segment (tergite) there is a band of brown or light brown hairs. On the last tergite the band does not appear divided. When viewed from above, the first tergite is shallowly indented and has a shallow V-shaped groove on the front margin. The sides of each tergite have a tuft of pollen-collecting hairs. The tufts often wrap to the upper side.

The wings are tinted brown. On the forewing there are three submarginal cells. The basal vein on the forewing is strongly curved (arced) inward.

The legs are black. On the middle legs the third segment (femur) is greatly swollen. The fourth segment (tibia) has no spurs at the end. On the hind legs the femur is swollen but not as much as on the middle leg. On the male the tibia has a large, flattened, triangular extension on the inside. There are two spurs on the extension. The last part of the leg (tarsus), corresponding to the foot, has five segments. The first segment on the hind leg is greatly elongated and has a fringe of hairs on the inside.

Size

Female Length: 9⁄16″ (14 mm)

Male Length: ⅝″ (17 mm)

Similar Species

Habitat

Prairies, corn and soybean crops

Ecology

Season

July through mid-September

Behavior

Life Cycle

Giant sweat bee is a solitary nester. The female builds a nest in the ground surrounded by a giant mound of excavated soil. The opening to the nest is at the base of the mound. While each nest is occupied by a single female, there are often many nests in a small area..

Larva Food/Hosts

Adult Food

Pollen and nectar of mostly prairie sunflower (Helianthus petiolaris) but also other sunflowers