
	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 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.

	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


	Biology
	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


	Adult Food


	Distribution
			Sources 4, 24, 27, 29, 30, 82.
	7/12/2022

	Occurrence
	Common in southern Minnesota


	Taxonomy
	Order	Hymenoptera (ants, bees, wasps, and sawflies)
	Suborder	Apocrita (narrow-waisted wasps, ants, and bees)
	Infraorder	Aculeata (ants, bees, and stinging wasps)
	Superfamily	Apoidea (bees and apoid wasps)
	Family	Sphecidae (thread-waisted wasps)
	Subfamily	Sphecinae
	Tribe	Sphecini
	Genus	Isodontia (grass-carrying wasps)

	Synonyms
	Sphex apicalis Sphex apicalis mexicana

	Common Names
	Mexican grass-carrying wasp

Glossary

Pronotum

The saddle-shaped, exoskeletal plate on the upper side of the first segment of the thorax of an insect.

Tegula

A small, hardened, plate, scale, or flap-like structure that overlaps the base of the forewing of insects in the orders Lepidoptera, Hymenoptera, Diptera, and Homoptera. Plural: tegulae.

Tarsus

The last two to five subdivisions of an insect’s leg, attached to the tibia; the foot. Plural: tarsi.

Tibia

The fourth segment of an insect leg, after the femur and before the tarsus (foot).


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	Alfredo Colon












	Babette Kis

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


	Whitey Com

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




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	Slideshows


	Digger Wasp (Isodontia mexicana) Andree Reno Sanborn

	About Summer World page 72: . . . I thought I saw a light-colored piece of straw about half a foot long "flying" horizontally and then hovering in midair. That caught my attention — I looked closer and saw a black wasp that seemed identical in form to a mud dauber, and it was carrying an object. I jumped up in my excitement, and the wasp was spooked and flew off. The proof eluded me, but it dropped its "prey" onto the porch. I picked it up — definitely a long piece of dry grass! Expecting the wasp to return, I waited. After about twenty minutes it did return, carrying another piece of grass. This time I was ready with an insect catcher net, and I snagged the wasp along with the grass it carried. The wasp was about 0.6 inch long, and the lbade it was carrying was about 2.4 inches long. The wasp looked superficially almost identical to the mud dauber, but its body was black rather than black-blue and its wings were smoky-colored instead of blue-black like the mud dauber's. It was a different species of wasp, which I later identified as Isodontia mexicana. I also learned later that rather than making clay organ-pipe cavities for its nest and filling them with spiders, this wasp lines preexisting cavities with grass and fills them with paralyzed crickets or katydids.

slideshow


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	Other Videos


	Isodontia mexicana 69Patchou

	About Published on Aug 28, 2009



	Guepe solitaire Isodontia mexicana:Ponte Marc Germain

	About Published on Mar 17, 2013

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Visitor Sightings

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		This button not working for you? Simply email us at info@MinnesotaSeasons.com. Be sure to include a location.



Alfredo Colon 8/11/2022	Location: Albany, NY



Alfredo Colon 8/2/2022	Location: Albany, NY



Whitey Com 7/10/2022	Location: Excelsior, MN Attempting to build a home in the support structure of a deck chair.



Babette Kis 7/15/2021	Location: Barnes Prairie, Racine Co., WI Isodontia mexicana, Mexican Grass-carrying Wasp on gray dogwood leaf. Barnes Prairie, Racine Co., WI July 15, 2021.



Alfredo Colon 8/16 to 8/18/2019	Location: Slinger, Wisconsin



Christine Gerjets 6/14/2019	Location: Glenwood MN; Pope County Building nest in window frame



Alfredo Colon 8/16/2018	Location: Woodbury, Minnesota



Alfredo Colon 6/8/2018	Location: Woodbury, Minnesota



MinnesotaSeasons.com Sightings