"The characteristic color of the galls is only in the epidermis, which is 1 cell layer thick. When the epidermis is peeled away, a mat of white fungal tissue can be seen below...hard, black carbonaceous material...encases the larva or larvae."

[He lists the following host records for this species, verified by both host and insect identification: Aster choralis [probably a Symphyotrichum cordifolium complex member], Aster ciliolatus [S. ciliolatus], A. coerulescens [probably a S. lanceolatum complex member], A. cordifolius [S. cordifolium], A. divaricatus [Eurybia divaricata], A. dumosus [S. dumosum], A. ericoides [S. ericoides], A. falcatus [S. falcatum], A. laevis [S. laeve], A. lateriflorus [S. lateriflorum], A. novae-angliae [S. novae-angliae], A. oblongifolus [S. oblongifolium], A. ontarionis [S. ontarionis], A. paternus [Sericocarpus asteroides], A. pilosus [Symphyotrichum pilosum], A. puniceus [Symphyotrichum puniceum], A. sagittifolius Wedemeyer [S. cordifolium], A. schreberi [E. schreberi], A. simplex [probably a S. lanceolatum complex member], A. undulatus [S. undulatum]]

[He also lists the following additional Symphyotrichum species as possible Asteromyia hosts based on observations of galls only (no insect material available). These gall records are included on this page because this midge species seems to specialize on this host genus, but see the "gallformers notes" for possible exceptions to this trend:
Aster anomalus [Symphyotrichum anomalum], A. azureus [S. oolentangiense], A. elliottii [S. elliottii], A. lowrieanus [S. lowrieanum], A. lucidulus [S. firmum], A. novibelgii [S. novi-belgii], A. occidentalis [S. spathulatum], A. praealtus [S. praealtum], A. sericeus [S. sericeum], A. shortii [S. shortii]]

- Raymond J. Gagné: (1968) A Taxonomic Revision of the Genus Asteromyia (Diptera: Cecidomyiidae)^©