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Genus Chalybion - Blue Mud-dauber Wasps

Large wasp - Chalybion californicum Wasp? - Chalybion californicum Unidentified Wasp - Sphecidae? - Chalybion californicum Unknown Hymenoptera - Chalybion californicum - female Chalybion californicum - female Male, Sphecidae - Chalybion zimmermanni - male Chalybion californicum Sphecid - Chalybion californicum
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Hymenoptera (Ants, Bees, Wasps and Sawflies)
No Taxon (Aculeata - Ants, Bees and Stinging Wasps)
No Taxon (Apoid Wasps (traditional Sphecidae))
Family Sphecidae (Thread-waisted Wasps)
Subfamily Sceliphrinae
Tribe Sceliphrini (Mud-dauber Wasps)
Genus Chalybion (Blue Mud-dauber Wasps)
Explanation of Names
Chalybion Dahlbom 1843
2 spp. in our area(1), 46 total(2)
One of two metallic blue genera in our area. Chalybion is separated from the superficially similar Chlorion by the following traits:
Head and thorax hairier, the vertex of the head particularly with noticeable setae
Antennae inserted higher, at or slightly above the halfway point of the eye.
The head is less produced at the temples and vertex
Mandibles are simple and sickle-shaped rather than dentate
Pronotum more strongly notched
Tarsal rake absent in females
Wing with the hind margin of the third sub-marginal cell strongly separated from the fore margin, resulting in a distinctly rhombic cell rather than a strongly triangular cell
Propodeum with at most a median sulcus or pit (Chlorion has a distinctive U-shaped dorsal enclosure with a distinct sulcus/furrow)
Generally smaller
Color is only bluish (Chlorion can also be greenish or purplish)

Overview of Species
Our spp. are defined based on features of metapleuron and metanotum (interactive key). For the populations within the US, the species (and subspecies) are separated in photography as follows:(3)
C. californicum: dark hairs, especially on the head and thorax, and dark wings

C. zimmermanni aztecum: white hairs, especially on the head and thorax, and clear wings

C. zimmermanni zimmermanni: white hairs, especially on the head and thorax, and dark wings
primarily Old World (mostly Afrotropical & Oriental)(2); in our area:(1)
Ch. californicum throughout the US into Canada (QC-ON, BC)
Ch. zimmermanni so. US to NC-IN-UT
Larvae are provisioned with spiders.
Life Cycle
Instead of building their own nests, nests of Sceliphron are often stolen and repurposed. The female uses water to re-mold the nest, typically resulting in a "lumpy" texture (as opposed to the smoother texture used by our species of Sceliphron). The contents are emptied, and new spiders are provisioned with the egg being laid on the final spider.
See Also