northeastern pebble bee

Northeastern pebble bee is an uncommon, small, solitary, wasp-like bee. It occurs in the United States from Maine to New York, west to Minnesota and Indiana, and in southern Ontario and Manitoba Canada.

Females are 5⁄16″ (8 mm) in length. The body is robust and black with yellow, pale-yellow, or white markings.

The plate on the face above the upper lip (clypeus) is slightly convex. The lower margin is straight and is not notched. The middle is black and there is a large yellow blotch on each side. On each side of the face, between the clypeus and the inner margin of the compound eye, there is a long, vertical, yellow mark. Each lateral face mark is broad below, and it borders the blotch on the clypeus. It is very narrow above, and it ends near the top of the eye. On each cheek there is a small yellow mark near the top of the eye. The jaws (mandibles) are entirely black, and they have three teeth. The middle tooth is conspicuous, the others less so.

The exoskeletal plates on the upper side of the thorax, from front to rear, are the pronotum, scutum, scutellum, and metanotum. The lateral lobes of the pronotum are expanded outwards, and the edges are paper thin and translucent. The small plates covering the wing bases (tegulae) are black with a large yellow spot. The scutum is black with a narrow, yellow, semicircular band on the rear margin that is interrupted in the middle. There is a small triangular area (axilla) adjacent to each front corner of the scutellum. The axillae are mostly yellow.

The first abdominal segment (tergite) has a yellow blotch on each side and a narrow band in the middle. Terga 2 through 5 have a band on each side, and the bands are widely separated from each other in the middle. The rear margin of each band is strongly indented. On the underside of the each abdominal segment there is a band of yellowish brown, pollen-collecting hairs (scopa).

The wings are rather deeply tinted smoky brown. The veins are brownish black.

The legs are mostly black. On each leg, the first segment (coxa) and second segment (trochanter) are entirely black. The third segment (femur) is black except for a small yellow mark at the tip. The fourth segment (tibia) on the front and middle legs is mostly yellow on the outer face. On the hind legs, the outer face of the tibia is yellow just at the tip. The last part of each leg (tarsus), corresponding to the foot, is rusty brown.

Males are larger than females, which is rare among bees. They are 5⁄16″ to ⅜″ (8 to 9mm) in length. The clypeus is broadly convex and entirely yellow. The outer face of each mandible is yellow, and the middle tooth is very low and inconspicuous. The axillae have a small yellow spot. The bands on terga 2 through 5 nearly meet in the middle. There is no scopa on the underside of the abdomen. On the front legs, the femur is entirely black. On the front and middle legs, the tibia is yellow on the outer face. On the front and rear legs, the first segment of the tarsus is yellow. On the rear legs, the coxa has a robust, long triangular, yellow spine.

Female total length: 5⁄16″ (8 mm)

Female total length: 5⁄16″ to ⅜″ (8 to 9mm)

July to September

The female builds an exposed nest using pebbles, leaves, plant hairs, resin, and soil, stuck to the surface of a rock or a twig. She provisions the nest with nectar and pollen. It may take up to 1,000 trips for the female to gather all of the varied materials she uses. The finished nest is well disguised with mud and pebbles, looking like debris on a rough surface.

Nectar and pollen

Sources

4, 24, 27, 29, 30, 82, 83.

Portman Z M, Gardner J, Lane I G, Gerjets N, Petersen J D, Ascher J S, Arduser M, Evans E C, Boyd C, Thomson R, Cariveau D P, plazi (2023). A checklist of the bees (Hymenoptera: Apoidea) of Minnesota. Plazi.org taxonomic treatments database. Checklist dataset https://doi.org/10.15468/qt7spn.

Small black and white wasp feeding on Leonard's Skullcap...

Blossoms. It was so quick and came in on the top corner of the frame so I just cropped it best I could to show it. It was at Frenchman’s Bluff SNA.

Dianthidium simile
Sam Droege

Dianthidium (Megachilidae)
Hymenoptera of North America

Dan W. Andree
7/5/2024

Location: Frenchman’s Bluff SNA

Small black and white wasp feeding on Leonard's Skullcap... Blossoms. It was so quick and came in on the top corner of the frame so I just cropped it best I could to show it. It was at Frenchman’s Bluff SNA.