Introduction Species list References 

 Chalybion californicum

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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