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Species Trichosirocalus horridus - Thistle Crown Weevil

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Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Coleoptera (Beetles)
Suborder Polyphaga
No Taxon (Series Cucujiformia)
Superfamily Curculionoidea
Family Curculionidae (Snout and Bark Beetles)
Subfamily Ceutorhynchinae (Minute Seed Weevils)
Tribe Ceutorhynchini
Genus Trichosirocalus
Species horridus (Thistle Crown Weevil)
Other Common Names
Musk Thistle Rosette Weevil, Musk Thistle Weevil, Rosette Weevil
Synonyms and other taxonomic changes
Trichosirocalus horridus (Panzer)
Orig. Comb: Curculio horridus Panzer 1801
3-5 mm
Body densely covered with brownish scales, which form no definite pattern. Additionally, dorsal surface with numerous stiff, erect setae.
native to Europe, introduced in NA for thistle control (map)(1)
feeds on the rosettes of thistles (Carduus & Cirsium spp., Asteraceae)(1)
Life Cycle
Female lays 500-800 eggs in clusters of 2 or 3 on the underside of leaves. Eggs hatch in 10-12 days. Larvae develop in basal portion of stem and root crowns. Complete development in 6-8 wks. Full grown larvae pupate in the soil in pupation chambers. Adults emerge in 12-20 days in the spring. They hide until the fall when they begin to feed. They overwinter as adults, eggs and larvae.
T. horridus was imported from Italy in 1970-1972 for testing and approved for field release in the USA in 1974. It first became established in VA and has since been relocated to many other states.(1) It is a very effective biocontrol of invasive musk and plume thistles. Unfortunately, it also feeds on some native thistles.
Internet References
Environ. Entomol. Occurrence of Trichosirocalus horridus (Coleoptera: Curculionidae) on native Cirsium altissimum versus exotic C. vulgare in North American tallgrass prairie.