Larval cells green, not lined with a white fungus...Contarinia partheniicola (Cockerell)

Galls are 5–8 mm long, 4–5 mm wide and are found on axillary buds, along stems, on young leaves, on flowers, and along the rachis of the inflorescence. Adults have been reared in spring and fall. Hosts: A. chamissonis, A. confertiflora, A. dumosa, A. eriocentra, A. psilostachya, and Parthenium...

Contarinia partheniicola

Contarinia partheniicola forms whitish, woolly, cupulate galls 5-8 mm long and 4-5 mm wide. Previously reported only from Parthenium, incanum, the type host, it is now known to occur on Ambrosia spp....R. D. Goeden writes (pers. comm.) that the galls on Ambrosia are formed singly or in small groups on various parts of the shoots, e.g., on axillary buds along the stems, on the young leaves, on the staminate florets, and along the rachis of the inflorescence.