Collection records from plants of several families have been reported for the rhopalids Arhyssus confusus Chopra and Arhyssus parvicornis (Signoret), but the hosts they use for nymphal development have remained unknown. During fieldwork in the southwestern United States from 2003 to 2009, mating pairs and nymphs of both rhopalids were found on globemallow, Sphaeralcea species (Malvaceae). Arhyssus confusus was collected at 37 sites from eight species of Sphaeralcea (Arizona, New Mexico, Texas, Utah), and A. parvicornis was collected at 18 sites from seven species of globemallow (Arizona, Colorado, New Mexico, Texas). Although both Arhyssus species might develop on other malvaceous genera or even on plants of other families, evidence based on extensive field collections suggests they are Sphaeralcea specialists. Notes on seasonal history and photographs of the adult dorsal habitus of the rhopalids are provided.