Euodynerus annulatus imperialis

(Bohart, 1945)

Euodynerus annulatus imperialis is a of in the Eumeninae. As a subspecies of the widespread E. annulatus, it shares the ' distinctive burrow-nesting , including construction of curved mud chimneys aboveground. The subspecies exhibits color and marking variations characteristic of the three western subspecies of E. annulatus. Females provision nests with paralyzed from Crambidae, , and .

Pronunciation

How to pronounce Euodynerus annulatus imperialis: /juːoʊˈdaɪnərəs ænjuːˈleɪtəs ɪmˌpɪəriˈælɪs/

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Identification

E. annulatus imperialis can be distinguished from the nominate and other eastern forms by coloration and marking patterns typical of western subspecies. The E. annulatus as a whole differs from the similar E. hidalgo by having a less propodeum (hindmost thoracic ) and hind margins of the first and second abdominal segments that are not clear and reflexed (turned up). Males have hooked tips on the and a less build than females. length ranges 8.5-10.5 mm.

Habitat

Found in situations close to water, as females regurgitate water to soften soil during nest construction. Nests are excavated in various soil , both hard and soft. have been observed taking nectar from early-blooming rabbitbrush (Ericameria sp.).

Distribution

Western North America. As one of three western of E. annulatus, its range falls within the western portion of the ' overall distribution, which extends from coast to coast in the United States, south to Mexico, and into Canadian provinces including British Columbia, Alberta, and Saskatchewan.

Diet

feed on nectar. are fed paralyzed from Crambidae, , and . Caterpillars of the Loxostege have been recorded as a major . Caterpillars are only weakly paralyzed and may remain somewhat ambulatory.

Host Associations

Loxostege - Major recorded by Rau and Rau
Crambidae - providing
Pyralidae - providing
Noctuidae - providing
Ericameria - NECTAR_SOURCE observed taking nectar from early-blooming rabbitbrush

Life Cycle

Females excavate burrows with several individual branching from the main underground tunnel. A curved mud chimney is constructed aboveground, later deconstructed to make the entrance flush with soil. A single is suspended from a short thread attached to the cell wall before provisioning with . Multiple caterpillars are placed in each cell. The nest entrance is sealed when all cells are provisioned, and the female begins a new nest.

Behavior

Females exhibit unique burrow-nesting among , constructing curved mud chimneys that serve both defensive purposes and as a source of mud pellets for final nest closure. visit flowers for nectar. Males are distinguished by hooked tips.

Ecological Role

of , particularly from containing agricultural pests. Contributes to of potential defoliators. may provide incidental while nectar-feeding.

Human Relevance

Like other , may be attracted to blocks and artificial nesting structures. The ' includes some agricultural , suggesting potential benefit in garden and agricultural settings.

Similar Taxa

Euodynerus hidalgoVery common and widespread; distinguished by more propodeum and reflexed, clear hind margins on first and second abdominal tergites
Euodynerus annulatus (nominate subspecies)Eastern form with different coloration and markings; E. annulatus imperialis is one of three western with distinct patterns

More Details

Subspecies variation

E. annulatus has five total, with three western and two eastern forms. Color and markings vary considerably among subspecies.

Parasites

No nest are recorded for this , but are vulnerable to the twisted- parasite Pseudoxenos hookeri, which causes visible bulges between abdominal .

Historical taxonomy

Described by Rau and Rau (1918) as Odynerus geminus (pages 300-312 in Studies Afield).