Latin Name:  Rhinocyllus conicus (Frölich, 1792)
                        (R. Bercha, det.)

Length:  3 to 7 mm

Range:  Alberta

Habitat:  Near Thistle

Time of year seen:  May to August

Diet: Musk Thistle and Plumeless Thistle

Other: This species is native to Europe and was imported to Canada in 1968 for biological control of Thistles.  Its main host is Musk or Nodding Thistle, however it will also attack Plumeless Thistle.  Each female lays from 100 to 200 eggs on the bracts of thistle heads. The eggs hatch in 6 to 9 days with newly hatched larvae feeding through the bracts into the receptacle. The larvae feed on the receptacle and the young seeds, preventing or reducing the production of viable seeds. There are a total of  four larval growth stages which last from 4 to 6 weeks. Pupation occurs in a black oval cell within the thistle head, and requires an additional 7 to 10 days. The adults emerge from the seed heads from July to August. They remain inactive and then hibernate through winter. The following spring the adults emerge from their winter refuge to lay eggs on new developing buds. There is only one adult generation each year. ( Boldt, P. E., 1985)