P. sarcobati forms a biconvex swelling on the leaves of S. vermiculatus which somewhat resembles the galls formed on Chrysothamnus spp. and Haplopappus spp. by Asteromyia chrysothamni Felt. [these hosts are now mostly in the genus Ericameria, with some exceptions]

Swollen, occasionally discolored leaf (251a).....Protaplonyx sarcobati (Felt)

Adults were reared in spring and summer, so there are probably several generations per year. Adults have an unusual ovipositor modified for piercing plant tissue. Host: S. vermiculatus. Distr.: Colorado and Utah. Ref.: Gagne (1969c).