Doug Hastings passed through a few groups in the mid- to late '60s, and is best known for his brief stint as a guitarist in Buffalo Springfield, filling in for Neil Young on one of the occasions in which Young left the group for a while. Before his temporary hitch in Buffalo Springfield, Hastings had been lead guitarist in the Daily Flash, a decent folk-rock-psychedelic group from Seattle that played around San Francisco and Los Angeles in 1966 and 1967. Unfortunately, they weren't allowed to realize their full potential, releasing just a couple of singles (including "Jack of Diamonds," which has some thrilling feedback guitar, presumably by Hastings). Other studio and live tracks recorded by the band came to light on the Daily Flash compilation I Flash Daily.
Hastings left the Daily Flash in May 1967, and was soon recruited to replace Young in Buffalo Springfield. Hastings was already known to Buffalo Springfield since they had the same managers as the Daily Flash. He was also familiar with their material and tried to play like Neil Young, but the rest of the bandmembers weren't entirely satisfied with the situation, particularly as Hastings (unlike Young) wasn't a songwriter. He did play some guitar during the sessions for their single "Bluebird," but these were cut out of the final version. He also played with the band at one of its most high-profile gigs, the 1967 Monterey Pop Festival (at which David Crosby joined them as a guest). He was also with the group at an August 1967 appearance in Whittier, CA, that has frequently been bootlegged. He told Buffalo Springfield biographer John Einarson that he played on the basic track of the group's classic "Rock and Roll Woman" (although he is not credited on the album), and that a lead part he contributed was mixed out.
Hastings was unceremoniously dumped in mid-August 1967 when Young decided to return, getting fired by Stephen Stills over the phone. He went on to join bloated psychedelic group Rhinoceros, who recorded a couple of albums, and played guitar on early records by singer/songwriter David Ackles; he also played with Dr. John and singer/songwriter Pamela Polland. As the 20th century neared its close, he was reportedly working in petroleum geology in Alaska.