lobed mason wasp

not listed

not listed

not listed

Lobed mason wasp is a medium-sized stinging wasp. It occurs in Europe and North America. In the United States it occurs in the east from Maine to North Carolina, west to Minnesota and Missouri, in the west from Washington to northern Idaho, and in Colorado. There are just a few scattered records outside of these areas. It is common in Minnesota.

Adults are black with yellow markings. The front part of the body (mesosoma) is connected to the rear part (metasoma) by a narrow waist (petiole).

Wasp size is often given in terms of the length of the forewing. The female has a 5⁄16″ to ½″ (8.0 to 12.5 mm) forewing length.

The head is black. There are two large compound eyes, one on each side of the head, and three small simple eyes (ocelli) in a triangular pattern at the top of the head between the compound eyes. The inner margin of each compound eye is notched. The antennae are thread-like and have 13 segments, including a long first segment (scape) at the base, a short second segment (pedicel), and a whip-like section (flagellum) with 11 segments (flagellomeres). The upper side of all antennal segments is black. The underside of the scape is yellow, forming a continuous stripe that is not narrowed in the middle. The underside of the pedicel and each flagellum is yellowish. The last flagellum is not hooked at the tip. The jaws (mandibles) are long and knife-like. The plate on the face (clypeus) is black with a yellow spot on each lateral margin and a pair of yellow spots on the lower margin. There is a yellow spot on the head between the antennae bases, and a small yellow spot (postocular spot) behind each compound eye.

The thorax is black and has three segments, the prothorax, mesothorax, and metathorax. However, the first segment of the abdomen (propodeum) is fused to the thorax, giving the thorax the appearance of having four segments. The upper plate on the prothorax (pronotum) is short and collar-like. It does not have a narrow transverse ridge (carina) on the front margin. It extends rearward on the sides to the plate at the base of each wing (tegula). It appears horseshoe-shaped when viewed from above, triangular when viewed from the side. It is mostly black except for a yellow band on the front margin of the upper (dorsal) surface. The band tapers narrowly to each side, narrows toward the middle, and is sometimes narrowly interrupted in the middle. On the mesothorax, the large front plate (mesoscutum or scutum) has a pair of distinct longitudinal grooves that effectively divide it into a central portion and two lateral lobes. This is the feature that gives the wasp its common name. The smaller rear plate (scutellum) has a pair of small yellow spots. The spots are variable, usually small, round, and widely separated, sometimes rectangular and narrowly separated. The upper surface of the metathorax (metanotum) is entirely black, with no yellow markings. The propodeum is shiny has two very prominent lateral ridges. There is a small yellow spot at the base of each forewing and a larger yellow spot on the side of the thorax below the wing bases. The first and second abdominal segments form a petiole that connect the abdomen to the thorax.

The upper part of the first segment of the metasoma (first tergite) is wider than long and only half as long as the second tergite. It is black with a yellow band at the rear. The second tergite has a broad yellow band at the rear and is almost as long as the remaining tergites combined. There is always a yellow band on at least the first through fourth tergites.

The wings are moderately tinted smoky brown and have dark veins. They are folded longitudinally over the body when at rest. On the forewing, the first discoidal cell is very long, about half the total length of the wing. There are three submarginal cells.

The legs are black and yellow. The first segment (trochanter) is not divided – it has just one segment. On each leg the third segment (femur) is mostly black, yellow just at the tip, and the fourth segment (tibia) is yellow above, black below. The tibia on the middle leg has a single spur at the tip. The last part of each leg (tarsus), corresponding to the foot, has five segments. There is a pair of claws at the tip of each tarsus. The claws are split (cleft) at the end.

The male is smaller, with a ¼″ to ⅜″ (7.0 to 10.0 mm) forewing length. The antennae have just 12 segments. The last flagellum is hooked at the tip. The spot between the antennae bases is smaller. The clypeus is entirely yellow. The postocular spot is sometimes very small. The spots on the scutum are smaller and are sometimes missing. The abdomen has seven visible segments. There is a yellow band on tergites one through six.

Female forewing length: 5⁄16″ to ½″ (8.0 to 12.5 mm)

Male forewing length: ¼″ to ⅜″ (7.0 to 10.0 mm)

Possibly two generations per year: Early June to early September (CCESR and BugGuide)

The wings are folded longitudinally over the body when at rest.

The female nests in a preexisting cavity, which could be a boring in wood, a hollow sumac or elderberry twig, or an abandoned mud dauber nest. The nest has multiple cells separated by a partition made of mud.

Caterpillars

Sources

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

Common

Location: Albany, NY

Location: Woodbury, MN