grass-carrying wasp

(Isodontia mexicana)

Conservation Status

IUCN Red List

not yet assessed

grass-carrying wasp (mexicana)



not listed


not listed




Two generations per year: May to October




Total Length: to ¾ (16 to 20 mm)

Male Average Length: (16 mm)

Female Average Length: (17 mm)

Photo by Alfredo Colon

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

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.



Larval Food


Adult Food


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.



Distribution Distribution Map  

Sources: 24, 27, 29, 30.


No Common Name
This species has no common name. The common name of the genus Isodontia is grass-carrying wasps, and is applied here for convenience.



Hymenoptera (ants, bees, wasps, and sawflies)



Apocrita (wasps, ants and bees)


No Rank:




Sphecoidea (vespoid wasps)



Sphecidae (digger wasps)



Sphecinae (thread-waisted wasps)








Sphex apicalis

Sphex apicalis mexicana


no common name









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



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.



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



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






Visitor Photos
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Alfredo Colon
  grass-carrying wasp (mexicana)   grass-carrying wasp (mexicana)
  grass-carrying wasp (mexicana)   grass-carrying wasp (mexicana) Photos



  Digger Wasp (Isodontia mexicana)
Andree Reno Sanborn
  Digger Wasp (Isodontia mexicana)  

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.

  grass-carrying wasp (Isodontia apicalis or mexicana)
Bill Keim
  grass-carrying wasp (Isodontia apicalis or mexicana)  



Visitor Videos
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Other Videos
  Isodontia mexicana

Published on Aug 28, 2009

  Guepe solitaire Isodontia mexicana:Ponte
Marc Germain

Published on Mar 17, 2013




Visitor Sightings
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Christine Gerjets

Location: Glenwood MN; Pope County

Building nest in window frame

Alfredo Colon

Location: Woodbury, Minnesota

grass-carrying wasp (mexicana)

Alfredo Colon

Location: Woodbury, Minnesota

grass-carrying wasp (mexicana)






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