Explanation of Names
Dianthidium Cockerell 1900
23 spp. in 3 subgenera in our area (all but 3 in the nominate subgenus), ~30 spp. in 4 subgenera total(1)
"The lamellate, expanded pronotal lobes and the convex, semicircular mesoscutellum margins are diagnostic for this genus" KJH (ref.
The pronotal lobes of Dianthidium have edges that are paper thin and translucent. Other Anthidiini have thin edges but never as thin as Dianthidium. (2)
As shown here with the arrows:
precinctive, or endemic, to NA (so. Canada to Costa Rica)(1)
They construct cells of pebbles glued together with resin and placed on twigs, or on roots below the soil surface, or in any available burrows or borings.