Half-belted blue-black spider wasp

Conservation Status

IUCN Red List

not listed

NatureServe

not listed

Minnesota

not listed

Description

Half-belted blue-black spider wasp is a medium-sized predatory wasp. It occurs in the United States from Maine to Florida, west to Minnesota, Nebraska, and Arizona. It also occurs in southern Ontario Canada.

Adults are active from June through August. They are found in open areas with sandy soil or clay. They prey on Wolf Spiders (Lycosidae) and Jumping Spiders (Salticidae). They primarily feed on nectar from a wide variety of wildflowers. While females have been observed consuming the hemolymph (blood) of their spider victims, this serves as a temporary protein boost to fuel the task of transporting prey to their burrows.

Females are 7⁄16″ to ¾″ (11 to 20 mm) in length, averaging ⅝″ (15.5 mm) in length. The body is bluish black.

The head is entirely black except there is often a narrow pale streak along the outer margin of each compound eye. The antennae are thread-like, they have 12 segments, and they are short relative to other members of the genus. They are often seen rolled up or coiled at the tip. This feature, common to all female spider wasps, allows it to “drum” the surface of the leaf litter (antennal palpation) and detect the chemical trail of its prey.

The thorax and abdomen are entirely black except for a broad orange band across the second visible abdominal segment (tergite 2).

The legs are long and black. The last part of each leg (tarsus), corresponding to the foot, has 5 segments. On the front legs, the last tarsal segment has a “comb” consisting of 3 to 5, usually 4, strong spines. On the rear legs, the last tarsal segment also has spines underneath. On all legs, the claws on the last tarsal segment are toothed (dentate).

The forewings are smoky dark and relatively short, typically not reaching beyond the tip of the abdomen. The marginal cell is about 2.5 times longer than wide, the second submarginal cell is usually about 1.5 times wider than long, and the third submarginal cell is usually triangular or nearly triangular.

Males are smaller, ¼″ to ⅝″ (6.5 to 17 mm) in length, averaging ½″ (12 mm) in length. The orange band on the abdomen frequently extends onto tergite 3. The tarsal claws are split (bifid).

Size

Female total length: 7⁄16″ to ¾″ (11 to 20 mm)

Male total length: ¼″ to ⅝″ (6.5 to 17 mm)

Similar Species

Habitat

Open areas with sandy soil or clay

Ecology

Season

June through August

Behavior

When hunting, the wasp moves in a frantic, zigzagging pattern across the ground, flicking its wings and drumming its antennae against the leaf litter. This “antennal palpation” allows it to detect the chemical signatures of silk trails or hormonal scents left behind by spiders. The rapid wing flicking is designed to startle a concealed spider into moving and revealing its position. Upon locating its prey, the wasp quickly delivers a sting to the spider's underside to paralyze it.

Life Cycle

Larva Food

Captured and paralyzed spiders

Adult Food

Flower nectar

Distribution

Sources

30, 82, 83.

Anoplius semicinctus (Dahlbom, 1843) in GBIF Secretariat (2023). GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org. Accessed 3/27/2026.