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Species guide - species detail

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Coelioxys moesta (Cuckoo bee)



Coelioxys is a genus in the Family Megachilidae that consists of cuckoo bees. Instead of building their own nests, these bees enter the nest of another bee and lay their eggs in the host cells. The Coelioxys larvae displace the host larvae and grow in their place.


All Coelioxys spp. have relatively long abdomens that taper to a distinctive point. They are generally less hairy than other bees and females have no pollen collecting hairs, as they do not collect pollen or build nests.

Nest Structure

Hosts: In Bee Atlas blocks, all holes that produced Coelioxys moesta also produced Megachile relativa, indicating a parasite/host relationship. One hole produced M. relativa and Osmia lignaria. However, as nests from multiple individuals can be stacked within holes and all other holes produced M. relativa, we consider O.lignaria unlikely to be a host. Medler and Koerber (1958) reported Coelioxys moesta to be a parasite of Megachile relativa; Medler (1959) recorded M. centuncularis as a host; and Medler and Lussenhop (1968) related that D. H. Pengelly reared C. moesta from the nests of M. texana and M. frigida, neither of which have been seen in Bee Atlas blocks. Hobbs (1968) noted C. moesta as a probable parasite of M. rotundata. A new host record is from an anonymous label on a pin with a female C. moesta from Tucson, Arizona from a nest of M. concinna.

Hole Sizes

No information at this time.


No information at this time.

Activity Period

No information at this time.


Baker J. R. 1975. Taxonomy of five nearctic subgenera of Coelioxys (Hymenoptera: Megachilidae). The University of Kansas Science Bulletin 50(12):649-730.

Minnesota Record Map

These data are from the Minnesota Bee Atlas project.

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