Cleonis

Cleonis species are distinguished by their cylindrical body shape, a defining trait of the tribe Cleonini. Within Curculionidae, Cleonini can be separated from related tribes by larval and pupal characteristics: larvae possess a well-sclerotized head capsule with distinct egg-bursters, and pupae have specific arrangements of setae on the pronotum and abdomen. Species-level identification requires examination of adult genitalia and rostral proportions.

Species occur in open, xeric habitats with sandy soils, including alluvial floodplains, sheep pastures, and sandy chernozem areas with herbaceous vegetation. Specific documented habitats include alluvial floodplains near Kamyana Mohyla Reserve (Zaporizhia Province, Ukraine) and Pishchanska Balka near Melitopol (Ukraine).

Palaearctic distribution spanning from the Iberian Peninsula to the Russian Far East, with northern limits at approximately 60°N in Scandinavia and 60–63°N in Sakha (Yakutiya), Russia. Common throughout Ukraine and central/southern Europe; rare in northern Europe. At least one species (C. pigra) is adventive in North America, established in the northeastern USA, southeastern Canada, and Atlantic region since 1919.

Based on documented study of C. pigra: adults and larvae feed exclusively on Asteraceae, specifically genera Carduus, Cirsium, Centaurea, and Onopordum. Diet for remaining species in genus is not documented.

• Carduus - food plantadults and larvae
• Cirsium - food plantadults and larvae, including C. arvense
• Centaurea - food plantadults and larvae
• Onopordum - food plantadults and larvae

For C. pigra: larvae develop endophagously inside fusiform galls formed on the root neck of host plants. Oviposition occurs at the base of the stem or root neck. Number of larval instars estimated using Dyar's law. Laboratory rearing successful at 20°C, 70% relative humidity, and 12-hour photoperiod. Life cycle details for other Cleonis species are not documented.

Adults and larvae are endophagous, feeding and developing within host plant tissue. Adults of C. pigra have been observed to coexist with Cyphocleonus achates in the same localities. In open habitats, adults become prey for carnivorous animals.

Some species have been evaluated as potential biocontrol agents against invasive thistles (e.g., Cirsium arvense), though C. pigra was rejected due to its wide host range that includes cultivated globe artichoke. The genus serves as prey for carnivorous animals in open habitats.

C. pigra has been investigated as a biological control agent for invasive thistles in North America but was rejected due to non-target feeding on globe artichoke. The species is known as a pest of milk thistle (Silybum marianum).

• CyphocleonusBoth genera belong to tribe Cleonini and share cylindrical body form; can coexist in same localities. Distinguished by differences in adult rostral structure and larval/pupal morphology.
• LixusRelated genus in subfamily Lixinae; both have elongated body forms. Lixus species typically lack the pronounced cylindrical compression and have different host plant associations.

• weevil
• cylindrical weevil
• root gall
• Asteraceae feeder
• Palaearctic
• Cleonini
• endophagous
• biocontrol candidate

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Cleonis pigra (Scopoli, 1763) (Coleoptera: Curculionidae: Lixinae): Morphological Re-Description of the Immature Stages, Keys, Tribal Comparisons and Biology