Frank Bolus was the youngest son of Harry Bolus* and a keen amateur botanist like his father. He helped care for Harry's herbarium while this was still kept at home. In 1899 he collected plants around Mafikeng where he was stationed during the Anglo-Boer War. He appears to have worked in Aliwal North for a time and collected there in 1903. The next year he accompanied his father to Johannesburg where they collected for a single day on the open grassy hills of Booysens. They also went on a collecting trip to Prince Albert and the Swartberg Mountains this year, bringing back many specimens. Around this time Frank, who was then living in Kenilworth, Cape Town, sent some 40 plants to Joseph Burtt Davy* who had just started a herbarium in the Transvaal Department of Agriculture.
In 1912 Frank married Miss H.M. Louisa Kensit* who had been his father's herbarium assistant from 1903 and curator of the Bolus Herbarium at the South African College since Harry's death in 1911. Louisa was completing Volume 3 of Harry's Icones orchidearum Austro-Africanarum extra-tropicarum..., which was published in 1913, and Frank painted nine plates for it. With Louisa as co-author he also published a "Key to the flora of the Cape Peninsula" in the Annals of the Bolus Herbarium (1914, Vol. 1), and the two of them, with R. Glover as third author, described the "Flowering plants and ferns collected on the Great Karasberg by the Percy Sladen Memorial Expedition, 1912-1913" in the Annals shortly thereafter (1914-1915, Vol. 1, in 4 parts).
Frank also developed an interest in ornithology and in 1907 became a member of the South African Ornithologists Union. In 1919, then living in Claremont, Cape Town, he was a foundation member of the South African Biological Society, and in 1922 became a life member of the Cape Natural History Club.