Asteromyia carbonifera

Larvae possess specialized mycangia—pocket-like structures on the ovipositor for storing fungal conidia. Adults are small, delicate flies typical of Cecidomyiidae. Galls on Solidago stems or leaves contain blackened, carbon-like fungal tissue, distinguishing them from other gall-forming insects on goldenrod. The association with Botryosphaeria dothidea is diagnostic for this species complex.

Associated with Solidago (goldenrod) host plants in open fields, meadows, and disturbed habitats where goldenrod grows.

Recorded from Vermont and elsewhere in the United States. GBIF distribution records indicate presence in the US, with iNaturalist observations suggesting a broader North American range.

Larvae feed primarily on the mycelium of Botryosphaeria dothidea, the symbiotic fungus that forms the gall structure. This represents a mycophagous diet within the context of an obligate mutualism.

• Solidago altissima - host plantPrimary host for gall induction; other Solidago species may be used
• Botryosphaeria dothidea - obligate mutualistic symbiontFungus forms gall structure; larvae feed on fungal tissue and transport conidia in mycangia
• Torymus capite - parasitoidParasitoid wasp whose attack is inhibited by the fungal symbiont

Females lay up to 300 eggs per oviposition event, depositing fungal conidia from mycangia alongside eggs. Larvae develop within the fungus-induced gall, feeding on Botryosphaeria dothidea mycelia. Pupation occurs within the gall. Adults are short-lived and produce a single batch of gametes during pupal development, then engage in multiple oviposition events.

Females actively collect and transport fungal conidia in specialized mycangia on the ovipositor, then inoculate host plant tissue during egg-laying. Clutch size varies based on maternal mortality risk: females facing higher mortality risk between oviposition events deposit larger clutches to maximize fitness through moderately fecund offspring rather than few highly fecund individuals.

Induces gall formation on Solidago through fungal mutualism, manipulating plant tissue development. The fungal symbiont provides physical defense against parasitoid attack by Torymus capite. Represents a rare example of obligate insect-fungus mutualism in gall-forming insects.

• Other Asteromyia speciesCongeneric gall midges may form similar associations with fungi or induce comparable galls on Asteraceae; differentiation requires examination of fungal symbiont identity and gall morphology
• Other Cecidomyiidae on SolidagoMultiple gall midge species inhabit goldenrod; A. carbonifera is distinguished by the black, carbon-like fungal gall tissue and documented association with Botryosphaeria dothidea

• gall midge
• mutualism
• mycophagy
• mycangia
• Botryosphaeria
• Solidago
• obligate symbiosis
• parasitoid defense

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Selective Pressures on Clutch Size in the Gall Maker Asteromyia Carbonifera
• Use of Symbiotic Fungus by The Gall Maker Asteromyia Carbonifera to Inhibit Attack by the Parasitoid Torymus Capite
• Dissecting the association between a gall midge, Asteromyia carbonifera, and its symbiotic fungus, Botryosphaeria dothidea