Terellia

Species identification relies on wing pattern, body coloration, and male genitalia structure. The tarbinskiorum group species share three pairs of black shining spots on the scutum. The virens group is characterized by specific wing and body coloration patterns, including entirely hyaline wings in some species. Male phallus structure, particularly the shape of the glans and tubular extension, provides critical diagnostic characters. Orange or yellow markings on the pleura (katepisternum, meron, anepisternum) are present in some species groups.

Habitats are defined by host plant distribution, primarily in grasslands, steppes, and open habitats supporting thistles and related Asteraceae. Mountain steppe has been documented for some species.

Palearctic distribution, with records from Europe, Russia, Central Asia (Kazakhstan, Uzbekistan), the Middle East (Iran, Armenia, Lebanon), and scattered records from North America (DK, NO, SE per GBIF). Specific species show more restricted ranges: T. hajastanica is known only from Armenia; T. korneyevorum from Iran; T. barughii from Iran and Armenia.

Adult diet unknown. Larvae feed on developing seeds and tissues within flower heads (capitula) of Asteraceae host plants.

• Carduus - host plantThistle genus; host for T. serratulae
• Cirsium - host plantThistle genus including Canada thistle; host for T. serratulae and T. ruficauda
• Picnomon - host plantHost for T. serratulae; P. acarna-associated population may represent distinct host race
• Centaurea - host plantKnapweeds; host for multiple species including T. virens group (C. kotschyi, C. polypodiifolia, C. daralagoezica, C. spectabilis, C. takhtajanii), T. hajastanica (C. pseudoscabiosa subsp. glehnii), T. freidbergi, T. ivannikovi
• Echinops - host plantGlobe thistle; host for T. korneyevorum
• Amberboa - host plantHost for amberboae species group
• Psephellus - host plantP. erivanensis recorded as host for T. odontolophi
• Oligochaeta - host plantO. divaricata recorded as host for T. barughii

Larvae develop within the capitula (flower heads) of host plants, feeding on developing seeds and floral tissues. Pupation occurs either within the capitulum or in plant stems. Adults emerge from infested flower heads. Specific timing varies with host plant phenology.

Females oviposit into flower heads of host plants. Host specificity varies: some species are monophagous or oligophagous, while others show broader host ranges with potential host race formation.

Seed predators of Asteraceae, potentially influencing plant population dynamics. Some species have been evaluated or employed as biological control agents for invasive thistles.

Terellia ruficauda has been deployed as a biological control agent for Canada thistle (Cirsium arvense), with larvae parasitizing seed heads and reducing plant reproductive output. Other species have been investigated for control of yellow starthistle and related weeds. Host specificity testing is required before introduction as biocontrol agents due to risk of non-target effects.

• OrelliaShares scutal spot pattern with tarbinskiorum group species but differs in male genitalia structure and host plant associations
• UrophoraAnother tephritid genus associated with Asteraceae; some species formerly confused with Terellia or used in similar biocontrol contexts
• AcanthiophilusPolyphagous tephritid also associated with thistles; host range overlaps with some Terellia species

• Tephritidae
• fruit flies
• Asteraceae
• thistles
• biological control
• seed predators
• Palearctic
• host-specificity
• flower head insects

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Revision of Terellia amberboae group of species (Diptera: Tephritidae)
• Terellia hajastanica, a new species of tephritid flies (Diptera: Tephritidae) associated with Centaurea pseudoscabiosa subsp. glehnii (Asteraceae) in Armenia
• A new species of Terellia (Diptera: Tephritidae) from Iran with a key to the species of the tarbinskiorum group
• New data on the morphology, distribution and host plants of three species of the Terellia virens group (Diptera: Tephritidae)
• First findings of two species of Tephritidae (Diptera) from Armenia, with a description of a new host-associated population of Terellia odontolophi Korneyev, 1993
• Genetic and morphometric variations in the Lebanese populations of the flower-head-infesting fruit fly, Terellia serratulae (Diptera: Tephritidae)
• Tephritids of knapweeds, starthistles and safflower: results of a host choice experiment and the taxonomy of Terellia luteola (Wiedemann) (Diptera: Tephritidae)