Stenodynerus ochrogonius
Bohart, 1944
A solitary mason wasp in the Eumeninae, originally described by Bohart in 1944. Currently treated as a synonym of Rhynchalastor ochrogonius in some taxonomic databases, though iNaturalist and other sources maintain it under Stenodynerus. Like other eumenine , females are predatory on caterpillars, which they paralyze and provision in nest for their larval offspring. Males have a distinctive antennal modification with the last segment folded like a finger against the adjacent segment. The has been documented in Colorado and California.
Pronunciation
How to pronounce Stenodynerus ochrogonius: /ˌstɛnəʊˈdaɪnərəs ˌɒkrəˈɡoʊniəs/
These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.
Identification
Difficult to distinguish from Parancistrocerus and other Stenodynerus based on live images alone; microscopic examination of specimens is typically required for definitive identification. Males can be recognized by the modified last antennal segment, which is folded like a finger against the preceding segment. The species is smaller and more ornately patterned than some other mason wasps in the same region.
Habitat
Associated with cavity-nesting situations including blocks, dead wood with borings, and hollow twigs. Observed in urban and suburban settings with flowering vegetation, as well as near Saltcedar (Tamarix) trees that attract diverse .
Distribution
Documented in Colorado (Colorado Springs area, El Paso County) and California (Benicia marina). The limited number of iNaturalist observations (14) suggests it may be underreported or genuinely uncommon.
Seasonality
active in June based on available observations; likely active through summer months when flowering plants provide nectar and caterpillar prey is available.
Diet
Females hunt caterpillars, which they paralyze and store as larval food. visit flowers for nectar, including Indian hawthorn (Rhaphiolepsis umbellata) and Saltcedar (Tamarix).
Life Cycle
Nests in pre-existing cavities such as borings or hollow twigs. are provisioned with paralyzed caterpillars, each receiving a single . Larvae develop on the stored prey, with presumably one per year though this is not confirmed.
Behavior
Females are solitary nesters that stake out and defend nest cavities. are flower visitors. The has been observed entering blocks alongside other cavity-nesting and bees, suggesting some for aggregated nesting situations despite solitary habits.
Ecological Role
of caterpillars, potentially providing of herbivorous Lepidoptera. As a cavity nester, contributes to the of insects using dead wood and stem . Serves as for parasitic including sapygids.
Human Relevance
Occasionally observed in backyard blocks and artificial nesting structures, providing opportunities for citizen science observation. No documented economic importance or pest status.
Similar Taxa
- Parancistrocerus speciesExtremely similar in size, coloration, and nesting habits; cannot be reliably separated from Stenodynerus ochrogonius from live images in most cases, requiring microscopic examination.
- Euodynerus speciesLarger mason wasps with which it co-occurs at flowers and nest blocks; distinguished by size and less patterning in most cases.