Genus Isodontia - Grass-carrying Wasps

Isodontia Patton 1880

6 spp. in 2 subgenera in our area(1), >60 spp. worldwide(2)

Medium-sized dark sphecids, often seen carrying grass to nests. C. auripes is distinctive (?) with its brown legs.

Much of our area(3)

Open areas, fields, grass

in NC: I. auripes Jun-Oct, I. azteca May-Oct(4); Jul-Aug in MI(5)

Adults take nectar. Larvae are fed Grillidae (particularly tree crickets) or other Orthoptera.(6)

Females make nests in a tree, hollow stem or other cavity, divide into sections and close with grass. They provision with Orthoptera (Tettigoniidae, Gryllidae). Can be two generations per year (I. mexicana in PA)

1. Larva 2. Cocoon and food remnants in hollow stem 3. Adult female 4. Adult male. 5. Parasitic fly's puparia.

grass-carrying habits, nest(7); nesting behavior of I. harrisi(8)

Taken from the Internet Reference below (Penn State): The adult wasps emerge from their cocoons in early summer, mate, and the females locate a suitable nest site. She collects blades of grass and grass and hay stems to line the nest cavity. The wasp can be seen flying through the air with the blades trailing beneath her. She lands at the hole and enters, pulling the blade in behind her. After the nest is prepared, she hunts for tree crickets (i.e., Oecanthus sp.), captures and paralyses them with her sting, and transports them to the nest. She deposits eggs in the nest and the emerging larvae will feed on the living, but immobile crickets. When the larvae reach the appropriate size (in 4–6 days at 70–75° F.), they spin a cocoon and pupate. The adult wasps emerge in 2–3 weeks. In Pennsylvania, Isodontia mexicana typically produce two generations per year.

These wasps commonly make their nest in the narrow track found above outer windows.