Thistle
Guides
Calephelis muticum
Swamp Metalmark
Calephelis muticum, known as the swamp metalmark, is a small riodinid butterfly with a restricted distribution across wetlands of the upper Midwest, Ohio Valley, Ozark Mountains, and parts of Arizona. The species is globally vulnerable (G3) and endangered in Illinois, with small, isolated colonies scattered across ten states. It is distinguished from the northern metalmark (Calephelis borealis) by habitat preference, wing morphology, and host plant associations. Conservation concerns center on habitat loss from wetland conversion, invasive species, pesticides, and fire suppression.
Cassida rubiginosa
Thistle Tortoise Beetle
Cassida rubiginosa, commonly known as the thistle tortoise beetle, is a leaf beetle in the subfamily Cassidinae native to Europe and Asia that has been introduced to North America, New Zealand, and other regions as a biological control agent for invasive thistles. The beetle derives its common name from the tortoise-like appearance of adults, whose elytra and pronotum form a shield-like covering over the body. Both adults and larvae feed on thistle foliage, with larvae possessing a distinctive defensive structure—a forked caudal appendage used to carry accumulated feces and exuviae as a mobile 'fecal shield' that deters predators. The species has demonstrated effectiveness in reducing thistle biomass and seed production, though its host range extends beyond the primary target to other Cardueae species.
Chaetostomella
Chaetostomella is a genus of fruit flies in the family Tephritidae, established by Hendel in 1927. The genus comprises approximately 16 described species distributed across the Palearctic region. At least one species, Chaetostomella cylindrica, exhibits host race formation on different thistle species, with documented genetic, morphological, and behavioral divergence between populations associated with Notobasis syriaca and Onopordum illyricum.
Cheilosia grossa
Large Bulb Fly, Foxy Bulb Fly
A large, robust hoverfly species in the family Syrphidae, widespread across Europe. Adults are active in early spring, visiting willow catkins and other early-flowering plants. The species is notable for its phytophagous larvae that tunnel within thistle stems and roots, causing characteristic plant damage. Males exhibit distinctive hovering behavior at head height, occasionally forming loose swarms.
Dicymolomia
Dicymolomia is a genus of crambid moths established by Zeller in 1872, containing approximately eight described species. The genus is placed in subfamily Glaphyriinae. Dicymolomia julianalis has been documented as a seed predator on musk thistle (Carduus nutans) in Tennessee, with larvae feeding within seed heads and reducing seed production. The genus has been recorded from the United States, including Vermont and Tennessee.
Larinus
Larinus is a genus of true weevils (family Curculionidae) comprising approximately 180 species, with the highest diversity in the Palaearctic region, particularly Turkey where over 50 species occur. These beetles are characterized by stocky, rounded bodies and are primarily associated with plants in the family Asteraceae. Several species have been introduced to North America as biological control agents against invasive thistles, though some have demonstrated non-target effects on native thistle species.
Larinus turbinatus
Turbine Cylindrical Weevil
Larinus turbinatus is a true weevil in the family Curculionidae, native to the western Palaearctic. The species name refers to its cone-shaped snout. It is oligophagous on thistles, particularly Carduus and Cirsium species. Females lay eggs in flower buds, and larvae develop within the flower head, typically resulting in one surviving larva per flower due to intraspecific competition. The species has been introduced to the United States.
Narnia femorata
Leaf-footed Cactus Bug
Narnia femorata is a leaf-footed bug (Coreidae) native to the southern United States and Central America. The species was introduced to Florida in the 1960s via nursery stock and is now fully established. It feeds primarily on cactus fruit, especially Opuntia species, using a long tube-like beak. Males possess enlarged, spiny hind femora used as weapons in male-male combat for territories on cactus pads bearing fruit. The species exhibits pronounced phenotypic plasticity, with body size, weapon size, and beak length changing seasonally in response to host plant fruit availability. Populations have been documented utilizing Cirsium thistle as an alternative host, representing a recent host range expansion.
Papaipema arctivorens
Northern Burdock Borer, Thistle Stem Borer Moth
Papaipema arctivorens, commonly known as the northern burdock borer or thistle stem borer moth, is a noctuid moth species found in eastern and central North America. The species is notable for its specialized larval feeding on thistle and burdock stems, with larvae boring into the pith of host plants. Adults have a wingspan of 27–39 mm. The species has been documented across a broad geographic range from Quebec to northern Georgia.
Paracantha gentilis
Paracantha gentilis is a tephritid fruit fly species described by Hering in 1940 from Wyoming specimens. The species has a complex taxonomic history, with several taxa described by Malloch in 1941 (mimetica, mimetica elongata, mexicana) and Aczél in 1953 (sobrina) later synonymized under P. gentilis when wing pattern variation proved continuous rather than discrete. It is the first Tephritidae species in which the median oral lobe of larvae was described, a character now known to be shared by all non-frugivorous Tephritinae. The species exhibits a bivoltine life cycle with distinct behavioral and morphological adaptations for exploiting Cirsium thistle flowerheads.
Rhinocyllini
Rhinocyllini is a tribe of weevils within the subfamily Lixinae, characterized by their association with thistles (Asteraceae: Cardueae). Members are recognized by their distinctive rostrum structure and have been studied for their potential as biological control agents against invasive thistle species. The tribe includes economically significant genera such as Rhinocyllus, which has been introduced to multiple countries to manage thistle populations.
Rhinocyllus
thistle head weevil
Rhinocyllus is a small genus of true weevils (Curculionidae) comprising four described species. The genus is notable for its specialized association with thistles in the subtribe Carduinae. The most widely known species, R. conicus, was introduced to North America in the 1960s as a biological control agent for invasive thistles including musk thistle (Carduus nutans), but subsequently revealed significant non-target impacts on native North American thistles, including threatened and endangered species. The genus is sister to Bangasternus.
Rhinocyllus conicus
thistle head weevil, nodding thistle receptacle weevil
Rhinocyllus conicus is a small true weevil native to Eurasia and North Africa, introduced to North America in 1969 as a biological control agent for invasive thistles. Adults are black with yellowish mottled hairs, up to 6 mm long, with a short snout. Females lay eggs on thistle flower heads, which larvae enter to feed on developing seeds and flower parts, preventing seed production. While effective at controlling invasive thistles like musk thistle, the weevil was found to attack native North American thistles as well, leading to cancellation of its distribution permits in 2000.
Trichosirocalus
rosette weevils, crown weevils
A genus of small true weevils native to the Palearctic region. Several species have been widely introduced to North America, Australia, and New Zealand as biological control agents for invasive thistles. The genus was historically treated as containing a single species, T. horridus, but integrative taxonomic studies using molecular and morphological data have revealed multiple distinct species with different host associations.
weevilbiological-controlthistleinvasive-species-managementCeutorhynchinaerosette-feederCeutorhynchiniBaridinaetaxonomic-revisionclassical-biological-controlCarduusCirsiumOnopordumPalearctic-nativeintroduced-speciesmolecular-systematicsintegrative-taxonomyunivoltineleaf-mineragricultural-pest-controlpasture-weed-managementspecies-complexhost-specificitymusk-thistleplumeless-thistleScotch-thistleIllyrian-thistlewelted-thistleItalian-thistlecrown-weevilrosette-weeviloviposition-behavioroverwinteringegg-stagelarval-stageadult-stagedecaying-organic-mattersoil-surfacenon-photosynthetic-leavesgreen-leavesleaf-midribspetiolesleaf-miningnotching-damagerosette-survivalflowering-stem-reductionseed-production-reductionrosette-mortalitypopulation-density-effectsmark-recapturedispersal-patternsartificial-diet-rearinglaboratory-culturevitamin-supplementationlyophilized-thistle-rootsergosterolcasein-hydrolysate7-dehydrocholesterolsucroselarval-survivaladult-longevityovipositionfemale-fecundityfield-cage-experimentsindividual-cage-experimentsgrowth-parameter-reductionpre-release-host-specificity-testingpost-release-monitoringestablishment-successrange-expansionforested-areasagricultural-landpasturesmall-farmscropsdisturbed-habitatsmeadowsdense-patchesrosette-size-preferencespatial-distributionselective-ovipositionautumn-egg-layingwinter-larval-developmentspring-pupationlate-summer-adult-emergencesoil-overwinteringplant-debris-overwinteringrachisleaf-dissectiondestructive-samplingnon-destructive-samplingsampling-biaslife-stage-detectionestablished-populationsmitochondrial-COInuclear-EF-1αmorphological-charactershost-plant-associationssynonymyspecies-validityintroduction-historyrelease-recordsestablishment-recordsOld-World-nativeNew-World-introductionSouthern-Hemisphere-introductionAustraliaNew-ZealandNorth-AmericaVirginiaSouthwest-VirginiaEuropeSpainFranceGermanyItalySwitzerlandAustriaScandinaviaDenmarkNorwaySwedenColonnelli-1979Panzer-1801Alonso-Zarazaga-&-Sánchez-Ruiz-2002Ceutorhynchinae-vs-Baridinaesubfamily-placementtribe-placementtrue-weevilsCurculionidaeColeopteraInsectaArthropodaAnimalia882-iNaturalist-observationsGBIF-recordsCatalogue-of-Life-acceptedNCBI-TaxonomyBulletin-of-Entomological-ResearchJournal-of-Applied-EcologyJournal-of-Entomological-ScienceAnnals-of-the-Entomological-Society-of-AmericaEnvironmental-EntomologyDOI-10.1017/s000748531500084xDOI-10.1046/j.1365-2664.2002.00747.xDOI-10.18474/0749-8004-22.4.324DOI-10.18474/0749-8004-22.4.330DOI-10.18474/0749-8004-24.4.465DOI-10.1093/aesa/73.6.694DOI-10.1093/ee/10.5.691Trichosirocalus horridus
Thistle Crown Weevil, Musk Thistle Crown Weevil
Trichosirocalus horridus is a Palearctic weevil introduced to North America in 1974 as a biological control agent for exotic thistles in the genera Cirsium and Carduus. Native to Europe, it has established populations across the United States, particularly in Virginia where it spread from 609 km² in 1981 to 4,345 km² by 1985. Adults feed on thistle rosettes while larvae develop internally in stems and crowns, causing significant damage to host plants. The species has shown nontarget impacts, feeding on native Cirsium species in Nebraska and Tennessee at rates comparable to target weeds.
Uroleucon cirsii
Large Thistle Aphid
Uroleucon cirsii, commonly known as the large thistle aphid, is a species of aphid in the family Aphididae. It is a phloem-feeding insect that specializes on thistles and related plants in the Asteraceae family. Like other members of the genus Uroleucon, it exhibits parthenogenetic reproduction during the growing season, forming colonies of females that reproduce without males. The species is known from Europe, with confirmed records in Belgium, Denmark, and Norway.
Urophora
thistle gall flies, gall flies
Urophora is a genus of tephritid flies distributed across the Palaearctic Region, with species exhibiting close associations with Asteraceae plants. Larvae of many species induce galls on stems or other plant parts of thistles and related plants. The genus includes at least 13 species in Karaman Province, Türkiye alone, with new species continuing to be documented. Urophora cardui, a well-studied species, forms multi-chambered stem galls on Cirsium spp. and serves as host for multiple parasitoid wasps.