Mexican grass-carrying wasp

Conservation Status

IUCN Red List

not listed

NatureServe

not listed

Minnesota

not listed

Description

Mexican grass-carrying wasp is a slender, solitary, thread-waisted wasp. It is common in the northern half of the eastern United States and adjacent Canadian provinces. It has also been recorded, but is not common, south to Florida and west to California. It is common in the southern half of Minnesota. It is found from May to October in fields and other grassy open areas.

Adults are ⅝″ to ¾″ (16 to 20 mm) in length. Females average ⅝″ (17 mm), slightly larger than males which average ⅝″ (16 mm).

The head, thorax, and abdomen are completely black. The thorax is covered with long, erect, white hairs. The shield on the first segment of the thorax (pronotum) is short. There is a small rounded lobe on each side of the pronotum that does not reach the small plate (tegula) at the base of the wing.

The abdomen is shiny. The first segment is contracted into a thin stalk (petiole), making the body appear “thread-waisted”. There is a small brown spot at the base of the first segment of the abdomen, where the abdomen meets the petiole. This feature is thought to be diagnostic for this species.

The legs are black. On the middle leg there are two spurs at the tip (apex) of the fourth leg segment (tibia). The tibiae on the hind leg sometimes has a reddish tint. The end part of the leg, corresponding to the foot, has five segments. The last (terminal) segment on the front legs have no teeth.

There are both apressed silver hairs on the face and head, and erect white and brown hairs on the face. The antennae are black. The first antenna segment is longer than the second.

The wings are clear and tinted smoky brown.

Size

Total length: ⅝″ to ¾″ (16 to 20 mm)

Male Average Length: ⅝″ (16 mm)

Female Average Length: ⅝″ (17 mm)

Similar Species

Habitat

Fields and other grassy open areas

Ecology

Season

Two generations per year: May to October

Behavior

When at rest, the wings are held spread out at an angle from the body.

Life Cycle

The female builds a nest in a pre-existing natural cavity, an abandoned nest of another speceis, or a track of a storm window, lining it with dry or drying grass. She then finds and paralyses a tree cricket, katydid, or grasshopper, and carries it back to the nest. She partitions the nest and lays a single egg in each section. When the eggs hatch, the larvae feed on the still living cricket. They pupate after 4 to 6 days and emerge as adults in 2 to 3 weeks.

Larva Food/Hosts

Adult Food

Distribution

Sources

24, 27, 30, 82, 83.

Biodiversity occurrence data published by: Minnesota Biodiversity Atlas (accessed through the Minnesota Biodiversity Atlas Portal, bellatlas.umn.edu. Accessed 10/18/2026).

Isodontia mexicana (de Saussure, 1867) in Bánki, O., Roskov, Y., Döring, M., Ower, G., Hernández Robles, D. R., Plata Corredor, C. A., Stjernegaard Jeppesen, T., Örn, A., Pape, T., Hobern, D., Garnett, S., Little, H., DeWalt, R. E., Miller, J., Orrell, T., Aalbu, R., Abbott, J., Abreu, C., Acero P, A., et al. (2026). Catalogue of Life (2026-08-26 XR). Catalogue of Life Foundation, Amsterdam, Netherlands. https://doi.org/10.48580/dgyy9