Mexican grass-carrying wasp

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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 found, 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 tibia 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.

Total length: ⅝″ to ¾″ (16 to 20 mm)

Male Average Length: ⅝″ (16 mm)

Female Average Length: ⅝″ (17 mm)

Fields and other grassy open areas

Two generations per year: May to October

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

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.

Sources

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

Common in southern Minnesota

Mexican Grass-carrying Wasp Isodontia mexicana

Isodontia mexicana, Mexican Grass-carrying Wasp on gray dogwood leaf. Barnes Prairie, Racine Co., WI July 15, 2021.

Attempting to build a home in the support structure of a deck chair.

Location:   Flower Mound, Texas

In two days we have had four of these wasps in our bathroom area. The first two flew toward us and seemed aggressive.  The next two seemed almost as if they were dying. We have had our house closed due to freezing temps. No pets, no open windows. Cannot find the source.  We don’t have other bugs - only an occasional spider.  Any info? Will they soon be gone?

Location: Albany, NY

Location: Louisville, KY

Location: 2515 Smith Valley Rd, La Crosse, WI

They are enjoying our red milkweed and elderberry flowers

Location: Albany, NY

Location: Albany, NY

Location: Excelsior, MN

Attempting to build a home in the support structure of a deck chair.

Location: Barnes Prairie, Racine Co., WI

Isodontia mexicana, Mexican Grass-carrying Wasp on gray dogwood leaf. Barnes Prairie, Racine Co., WI July 15, 2021.

Location: Slinger, Wisconsin

Location: Glenwood MN; Pope County

Building nest in window frame

Location: Woodbury, Minnesota

Location: Woodbury, Minnesota