The larvae of the genus Rhyacionia are feeders on the buds and new growth of various species of pines, forming resinous exudations ; but never pitch nodules as in the genus Petrova.
We find in the literature mention of a single species infesting the buds of pines in California. The present study, however, has shown the existence of two species, Rhyacionia pasadenana (Kearf.) confined to Monterey pine and other pines along the coastal areas of California and Rhyacionia zozana (Kearf.) confined primarily to ponderosa pine and Jeffrey pine of the Sierra Nevada. Specimens of the former species reared from Monterey pine, Pinus radiata Don., were compared with specimens of the type series by Carl Heinrich and were found to be unquestionably this species. Specimens of the latter species reared from ponderosa pine, Pinus ponderosa Lawson, were compared with the type of Petrova zozana Kearf. in the American Museum by Carl Heinrich and a female found to agree in every detail with the Kearfott type. This makes it necessary to transfer Petrova zozana Kearf. to Rhyacionia, and makes Rhyacionia montana (Busck) at the most, a variety or race of zozana.