Stenodynerus histrionalis

(Roberts, 1901)

Species Guides

Stenodynerus histrionalis is a solitary mason wasp in the Eumeninae, native to western North America. The is difficult to distinguish from similar such as Parancistrocerus based on external alone, often requiring microscopic examination of specimens. Females are known to provision nests with paralyzed caterpillars as food for their larvae. Males possess a distinctive antennal modification: the last segment is folded like a finger against the adjacent segment.

Pronunciation

How to pronounce Stenodynerus histrionalis: //ˌstɛnoʊdaɪˈnɪərəs hɪˌstriːəˈneɪlɪs//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Stenodynerus histrionalis cannot be reliably distinguished from Parancistrocerus based on images of live specimens. Even with specimens under a microscope, separation from similar is difficult. Males may be identified by the distinctive antennal modification: the last segment folded like a finger against the adjacent segment. The species is currently classified under Stenodynerus but has been treated as Rhynchalastor histrionalis in some taxonomic treatments.

Habitat

Associated with cavity-nesting including pre-existing tunnels in dead wood, old borings, and artificial structures such as blocks or bee condos. Observed in riparian and disturbed habitats where flowering plants provide nectar resources.

Distribution

Western North America; recorded in Colorado and California. The has been documented in Colorado Springs, Colorado, and at the Benicia marina in California.

Seasonality

Active during summer months; observed in June in Colorado and California.

Life Cycle

Nests in pre-existing cavities. Females provision with paralyzed caterpillars as food for larval offspring. Larvae develop on this prey within partitioned cells.

Behavior

Solitary nesting . Females hunt caterpillars to provision nest . Both sexes visit flowers for nectar. Males have been observed foraging on Indian hawthorn (Rhaphiolepsis umbellata).

Ecological Role

of caterpillars; contributes to natural control of lepidopteran . Visits flowers for nectar, potentially contributing to pollination.

Human Relevance

Occasionally occupies artificial blocks or bee condos installed for solitary bees and . Not known to be aggressive toward humans.

Similar Taxa

Parancistrocerus speciesCannot be distinguished from Stenodynerus histrionalis based on images of live specimens; requires microscopic examination and even then separation is difficult
Euodynerus speciesSimilar cavity-nesting mason wasp and ; Euodynerus generally more robust with different facial markings

More Details

Taxonomic Note

Stenodynerus histrionalis has been treated as Rhynchalastor histrionalis in some classifications. The is currently listed as a heterotypic synonym of Rhynchalastor histrionalis in some databases, though iNaturalist and other sources maintain it under Stenodynerus.

Identification Challenge

The difficulty in distinguishing Stenodynerus from Parancistrocerus in the field highlights a broader challenge in eumenine , where many require detailed morphological examination for reliable identification.