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Lixus cardui is a successful biocontrol agent against scotch thistle already introduced to Australia. Lixus filiformis is a potential biocontrol agent for musk thistles in native distribution areas in the Palearctic. Mature larvae of both Lixus Fabricius species collected from Onopordum acanthium and Carduus nutans are described, illustrated and comparative remarks presented.

The mature larva of Larinus latus (Herbst) (Coleoptera, Curculionidae), a potential biological control agent for Onopordum spp. thistles introduced into Australia in 1992 for that purpose, is described and its taxonomically relevant features are illustrated.

The biology of Larinus latus (Herbst) (Coleoptera, Curculionidae), a weevil associated to one of the most serious pasture weeds in Turkey, Onopordum bracteatum, has been studied in Erzurum during 1999-2001. Adults migrated to lowlands at the beginning of June and fed on the leaves, capitula, and pollen of O. bracteatum. Females laid eggs on bracts, in the florets, and in stems of capitula. The larvae hatched at the beginning of July and fed on the base of capitula, florets, and seed. Mature larvae produced pupal cells in the margins of capitula and then pupated after the third week of July. The new generation of adults emerged from pupae from early August to the beginning of September, and 3-5 days after emergence migrated to higher altitudes approximately 2400 m for overwintering. The species completed one generation per year in Erzurum conditions.