Eastern thistle longhorn bee

Description

Eastern thistle longhorn bee is a medium-sized, ground-nesting bee. It occurs in the United States and southern Canada east of the Great Plains, but it is absent from the deep south.

Adults are active from late June to early October. They are oligolectic, meaning they collect pollen from only thistles (Cirsium spp.), but they will take nectar from many other flowers.

The female is ½″ to 9⁄16″ (12.0 to 13.5 mm) in length. The body is black.

The head is as wide as the thorax, and it is entirely black except for a yellowish spot at the tip of the mandibles. The plate on the face (clypeus) is entirely black, it is not lobed, and it rather strongly sticks out. The top of the head (vertex) is flat, not rounded, causing the simple eyes (ocelli) to bulge out. The hairs on the head are mostly white, but there is a fringe of black hairs on the rear of the vertex. The antennae have 12 segments, a long scape at the base, a short pedicel, and a whip-like section (flagellum) with 10 segments (flagellomeres). The first flagellomere is twice as long as the shorter side of the second. The flagellomeres are black above, brownish yellow on the underside.

The thorax has mostly whitish hairs. The largest plate on the upper side of the thorax (scutum) has mostly black hairs, but there is a band of white hairs at the front that continues narrowly around on the sides. The hairs are not dense enough to obscure the black surface of the scutum. The small plate on each side above the base of the wing (tegula) is tapered on one side, giving it a tear-drop shape. This is a defining feature of the genus Melissodes, but it is hidden beneath long hairs and cannot be seen without scraping the hairs away.

The first abdominal segment (tergite) has rather abundant erect, whitish hairs at the front and on the sides. Tergites 2 through 4 have a broad, translucent band on the rear margin, and are covered with black hairs at the front.

The legs have mostly short white hairs, but on the front and middle legs there is a patch of brownish-black hairs on the outer surface of the fourth leg segment (tibia). The pollen-collecting hairs (scopa) on the tibia of the hind leg are creamy white, short, and densely feather-like (plumose). The scopa are specially adapted for handling the unique characteristics of Cirsium pollen, which is why the females are so often seen with their fluffy scopa packed with bright white pollen.

The wings are clear at the base, becoming lightly tinted brown near the tip. The veins are brownish to brownish black.

The male is 7⁄16″ to 9⁄16″ (11.0 to 13.5 mm). The clypeus is yellow.

Size

Female total length: ½″ to 9⁄16″ (12.0 to 13.5 mm)

Male total length: 7⁄16″ to 9⁄16″ (11.0 to 13.5 mm)

Similar Species

Habitat

Ecology

Season

Late June to early October

Behavior

Life Cycle

Larva Food/Hosts

Cirsium pollen

Adult Food

Nectar from many genera of flowers