Genus: Dianthidium Cockerell 1900
Subgenera: Adanthidium, Deranchanthidium, Dianthidium, Mecanthidium
Common name: none
Dianthidium have robust, slightly elongate bodies ranging in body length from 5.5–23 mm. They have black or dark brown integument with white to yellow, or red in the subgenus Mecanthidium, maculations on their head, thorax, and abdomen (Michener 2007). Coloration of the body is largely variable, especially in males, and cannot be used exclusively in identification (Michener 2007). The abdomen is often curled under the body when active.
Dianthidium contains approximately 28-30 species in 4 subgenera worldwide; 21-23 species in 3 subgenera occur in the U.S. and Canada.
(modified from Michener 2007 unless otherwise stated)
Dianthidium may be confused with other Anthidiini, such as Anthidium and Anthidiellum, due to similar rounded, thick bodies patterned with yellow or white. However, the combination of the lamellate, produced pronotal lobes and carinate omaulus help to distinguish Dianthidium (Michener 2007).
There are no known invasives.
Dianthidium are solitary but are known to nest in aggregations. Nests are built in exposed riverbanks, holes in the soil, sand dunes, or among plant roots (Wilson and Carril 2016). Nests are also built above ground in preexisting natural cavities in wood, hollow stems, or rock crevices, as well as in exposed areas on rocks or twigs (Wilson and Carril 2016). Nests are composed of pebbles, sand, and occasionally pieces of plants with resins. Nests consist of one or more cells in a single chamber or as separated clusters of cells and sometimes with a parchment-like membranous lining (Grigarick and Stange 1968).
Dianthidium occurs in the Western Hemisphere, ranging from southern Canada through southern Mexico (Michener 2007). In the U.S. and Canada, they are most diverse in the west and are rare in the east, except for D. simile, which occurs in the eastern U.S., D. curvatum, which occurs transcontinentally, and D. floridiense, which is endemic to Florida (Wilson and Carril 2016). Dianthidium is uncommon in most of Canada with the exception of D. simile in southern Ontario, D. ulkei in central to western Canada, and D. subparvum in western Canada (Wilson and Carril 2016).