Scientific Name: Melissodes rivalis Cresson, 1872
Common Name: Rival Long-horned Bee
Melissodes rivalis Cresson, 1872: 277 
Lectotype m. USA, Texas [ANSP].
Melissodes desponsiformis Cockerell, 1905: 320  [synonymy by LaBerge 1956: 568]
Type f. USA, Oregon, Corvalis [presumed lost, as per LaBerge 1956: 575].
Melissodes mysops Cockerell, 1905: 146  [synonymy by LaBerge 1956: 568]
Melissodes hexacantha Cockerell, 1905: 100  [synonymy by LaBerge 1956: 568]
Melissodes nigrosignata Cockerell, 1905: 101  [synonymy by LaBerge 1956: 568]
Melissodes habilis Cockerell, 1925: 229  [synonymy by LaBerge 1956: 568]
Aspecies of the nesting biology of this species was described by Scullen (1928, as M. mysops) and summarized by LaBerge (1956), the former who reported on a large nesting aggregation in a sandy bank along the coast of Oregon. LaBerge (1956) indicated that nesting in large groups is rather unusual for Melissodes. LaBerge (1956) indicated that M. rivalis (and the other species of Heliomelissodes, M. disponsus) is oligolectic on Cirsium.
Pollen Specialization: Narrow Oligolecty
Wintering Stage: Mature Larva
Crop Preference: Not Available
Non Crop Preference: Cirsium sp.
Distribution: Alberta, British Columbia, Manitoba, Saskatchewan
Ecozone: Prairie, Western Interior Basin