The adults feed on the flower nectar of various flowers, including Silene, Carduus, Cirsium and Scabiosa species.
They feed on the flower nectar of various flowers, including Centaurea, Carduus and Knautia species.
The genus's most infamous species is R. conicus which is a controversial agent of biological pest control which has been used against noxious thistles in the genera Carduus, Cirsium, Onopordum, and Silybum.
It is a biological pest control agent that was introduced into the United States in 1974 to control exotic thistles, especially in the Cirsium and Carduus genera.
They suck nectar of the preferred blue violet flowers, such as on field scabious (Knautia arvensis), Dove Pincushion Flower (Scabiosa columbaria), meadow knapweed (Centaurea jacea), panicle knapweed (Centaurea stoebe), creeping thistle (Cirsium arvense), Bulbous thistle (Cirsium tuberosum) and ring thistle (Carduus).