"In typical galls of A. modesta there is usually some purple on the gall or on the surrounding area. In the latter case, the tissue immediately above the larva remains green. On Grindelia the gall tissue is occasionally hardened but there is no carbonaceous material typical of the other species of Asteromyia. There is only 1 larva/gall."

[Host records: Conyza canadensis, Erigeron strigosus, Grindelia hirsutula, G. humilis, G. robusta, G. squarrosa, Solidago flexicaulis, S. macrophylla]

[See this page for the Grindelia galls]

...modesta. Widespread eastern Nearctic, Brazil (Minas Gerais), Argentina (Buenos Aires). Conyza canadensis [Erigeron canadensis]; Erigeron strigosus (Asteraceae).

[They omit previous host records in Solidago and Grindelia in this catalog entry. The Grindelia omission aligns with their acceptance of Asteromyia grindeliae (presumably those galls belong to that species, which was previously held by Gagné to be a synonym of A. modesta), but the Solidago omission is less clear. The Solidago host records given in earlier resources are therefore provisionally retained here.]

Asteromyia species were identified using characters of mature larval and pupa (particularly the shape of the sternal spatula) using Gagné (1968) and with reference to gall morphology and host-plant affiliation (Gagné, 1968, 1994). All galls were categorized as to whether a thick mat of fungal hyphae or hyphal stroma was present or absent.
...
[from Appendix A – "Samples used mtDNA analyses with host-plants, collection site, and Genbank accession number", hosts sampled included: Erigeron canadensis, Erigeron annus, Solidago altissima, Solidago flexicaulis, Solidago gigantea, Solidago ohioensis, Symphyotrichum cordifolium, Symphyotrichum lateriflorum, Symphyotrichum sp.]

This specimen [one adult] emerged from an inconspicuous spot gall in a leaf of Erigeron speciosus (Lindl.) DC. (Asteraceae) that was collected to rear a leafminer (Fig. 7).

This species is less common on goldenrod than A. carbonifera and, unlike the latter, does not have a fungus associated with it but lives simply in the mesophyll layer of the leaf and forms only a single convexity on the leaf. Hosts Erigeron spp., Conyza spp, Grindelia spp.

Blisters are often inconspicuous unless discolored... This gall midge is multivoltine, each succeeding generation appearing on newer leaves.