Chalybion californicum (Saussure) 1867. The blue
mud-dauber is distributed transcontinentally, from southern Canada to
northern Mexico (Krombein 1979), and is likely to be found in most
areas of Michigan. There are few records from the UP, presumably from
lack of collecting.
BIOLOGY: This species nests in sheltered locations such as
sheds, under eaves of buildings, or beneath bridges, and usually
appropriates old or recently abandoned nests of Sceliphron
caementarium (Drury). Wasps carry water to manipulate mud
previously placed there by Sceliphron, rather than carry mud
as does S. caementarium. As a result of the reworking of the
mud, nests of C. californicum have a rough, lumpy texture,
versus the smooth, ''fnished" appearance of fresh S.
caementarium nests. Rarely, C. californicum reopens a
recently provisioned nest of S. caementarium, removes the
prey, and usurps the nest for her own provisions (Rau 1928).
Chalybion californicum mass provisions each cell with spiders,
usually from the families Theridiidae and Araneidae occasionally
Oxyopidae, Thomisidae, and Salticidae (Horner and Klein 1979,
Krombein 1979). This wasp has gained notoriety due to its preying on
black widow spiders (Latrodectus spp.) (Rau 1935a, Horner and
Klein 1979). Wasps have been observed catching araneids by landing on
the orb webs, enticing the spiders out from their retreat and
capturing them without becoming entangled in the spider's web
(Coville 1976). Perennial sleeping aggregations have also been noted
(Ward 1972).
FLOWER RECORDS: Berberis vulgaris, Daucus carota, Zizia
aurea.
COLLECTION DATES: 230 specimens, 25 May to 9 September. Most
dates are between late June and early August.
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