Forster wrote his first paper on spiders at the age of 17. Over the course of his career, more than 100 scientific papers and volumes were published bearing his name, including the definitive six-volume Spiders of New Zealand, in co-authorship with international colleagues. He also published Small Land Animals and co-authored NZ Spiders, An Introduction.[2] Much of his work was accomplished in collaboration with his wife, Lyn Forster, a notable New Zealand arachnologist.[6]
He researched and classified many of New Zealand's thousands of native spiders, and was responsible for establishing Otago Museum's spider collection.[2]
In 1961, Forster was elected a Fellow of the Royal Society of New Zealand, and received two of that society's honours: the Hutton Medal in 1971; and the Hector Medal in 1983.[1]
The University of Otago honoured Forster with the award of the degree of Doctor of Science, honoris causa, in 1978.[1]