Twenty-one species of arthropods were found associated with the pitchers of Darlingtonia californica Torrey 1853. D. californica pitchers were collected from three seeps located within a 3-km radius of each other, in the Klamath Mountains in northern California. Immature insect stages were reared in pitchers in the laboratory, and reared adults were collected and identified. New arthropod-plant associations were recorded for 15 arthropods, and an undescribed species was collected in each of the genera Corynoptera (Diptera: Sciaridae), Nartshukiella (Diptera: Chloropidae), Aspilota (Hymenoptera: Braconidae), and Macrosiphum (Homoptera: Aphididae). Host-parasite relationships were identified between Aspitola n. sp. and the larva of Megaselia orestes (Diptera: Phoridae), and between Orgilus strigosus Muesebeck (Hymenoptera: Braconidae) and the caterpillar of Udea (?) sp. (Pyralidae: Lepidoptera).