Studies on Haltica carduorum Guerin (Coleoptera:Chrysomelidae) on alien beetle released in Britain as a contribution to the biological control of creeping thistle, Cirsium arvense (L.) Scop.
Adults of Altica (Haltica) carduorum Guer. from France were released in 1969 and 1970 on Cirsium arvense (creeping thistle) at Silwood Park, Berkshire, and at three sites west of Cardiff in South Wales. Beetles were also released and studied in field cages. One generation was completed in the year of release, but only in a field cage were beetles found the following year. Egg production was low and mortality high at all stages. Observations on behaviour and activity, and on development in the laboratory, are described. It is concluded that A. carduorum is imperfectly preadapted to the climate in Britain and is unlikely to become more than very locally abundant. Its tendency to aggregate in the field and damage only a few plants in a stand does not make it a very promising insect for the biological control of Cirsium.