Bembix americana comata
J. Parker, 1917
Western Sand Wasp
Bembix americana comata is a of sand wasp in the Crabronidae, native to western North America. It is a solitary digger wasp that constructs burrows in loose sand to provision with paralyzed flies for its larvae. The subspecies is part of a variable where nest architecture shows -level variation in number. are active during warmer months and are commonly observed on barren sand exposures.
Pronunciation
How to pronounce Bembix americana comata: /ˈbɛmbɪks əˌmɛrɪˈkeɪnə koʊˈmɑːtə/
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Identification
Distinguished from tiger burrows by rounder entrance shape and coarser, piled diggings rather than fanned patterns. As a member of Bembix americana, it likely shares the ' general body plan but subspecific identification requires examination of morphological characters separating it from B. americana spinolae and B. americana hamata. The Seattle studied was considered intermediate between comata and spinolae at the subspecific level.
Habitat
Deep, dry sand barrens and loose sand exposures; sand prairie remnants with sparse vegetation. Requires substrates suitable for excavation of nesting burrows.
Distribution
Western North America; recorded from Washington state and Missouri sand prairies. Part of a with broader distribution across North America.
Seasonality
Active in spring and fall; observed in early autumn in Missouri when cooler temperatures limit activity of other sand-dwelling insects. Nesting activity documented during summer months (June–August) in Pacific Northwest .
Diet
females provision nests with flies (Diptera), which they capture, sting to paralyze, and transport to burrows. As many as twenty flies may be provided for a single larva, with prey quantity increasing as the larva grows.
Life Cycle
Solitary nesting with : females dig burrows, create , and provision them with paralyzed flies. Some construct multi-celled nests, though single-celled nests are more common. Larvae develop on stored prey within the burrow.
Behavior
Females engage in active parental care through , adding more prey as larvae grow. Burrow construction produces distinctive round entrances with coarse, piled diggings. have been observed following human observers for extended periods.
Ecological Role
of flies; contributes to regulation of dipteran . As a sand , it is a characteristic component of sand prairie and barren sand .
Human Relevance
Subject of behavioral and nesting studies due to its accessible and observable nesting habits. Burrows can be confused with those of tiger beetles by observers.
Similar Taxa
- Tiger beetles (Cicindela spp.)Create similar burrows in sandy substrates; distinguished by fanned diggings and more oval burrow entrances versus rounder shape and coarser pile of Bembix
- Ammophila proceraAnother thread-waisted wasp found in similar sand prairie ; distinguished by distinctive silver thoracic markings and use of caterpillar prey rather than flies
- Bembix americana spinolaeEastern ; morphological and geographic separation, with comata occupying western range
- Bembix americana hamataAnother in the complex; precise distinguishing characters require examination
More Details
Taxonomic history
Formerly placed in Sphecidae; now classified in Crabronidae. The subspecific status of western has been debated, with some populations showing intermediate characteristics.
Nesting variation
Study of Seattle revealed unexpected multi-celled nests, previously considered rare in this . This variation may reflect plasticity in response to local conditions or population-level differences.