Alice Pegler, daughter of S. Mackin Pegler and his wife Ellen, was educated at the Dominican Convent, King Wiliam's Town, and became a teacher. However, she suffered from poor health and eye problems all her life and in the eighteen-nineties gave up teaching to settle at Kentani, a village in the Transkei. Here she lived with her brother-in-law, H.P. Abernethy*, as governess and teacher to his daughters. For many years she collected natural history specimens, particularly plants and mainly within about 8 km of Kentani. At first her specimens were presented to the Public Museum, King William's Town (later the Kaffrarian Museum), for in the annual report of the King William's Town Naturalists Society for 1896 she is listed as one of its frequent contributors of specimens. In 1903 she visited the Transvaal and collected plants around Rustenburg and Johannesburg.
Miss Pegler later donated plant specimens to the herbaria of various local museums and corresponded with several leading South African botanists. For example, she sent plants to Dr. S. Schonland* at the Albany Museum, Grahamstown (1903, 1905, 1906, 1909, 1910), including some rare plants from Rustenburg (1903); to the South African Museum (1905-1907, 1909), where the herbarium was under the supervision of Professor H.H.W. Pearson*; and to the colonial botanist, P. MacOwan* (1904, 1904/5). MacOwan stated in his report for 1904/5 that she had just collected the Asclepiadaceae around Kentani with a view to the revision of this family in the next section of the Flora Capensis. She also corresponded with, and sent a large collection of plants, including many orchids, to H. Bolus*, who figured some of them in Volume 2 of his Ichones Orchidearum... (1911). He named many of her specimens and passed on a portion of her finds to Kew Gardens in England. She often visited the Bolus Herbarium and South African Museum herbarium in Cape Town. Her catalogue "On the flora of Kentani" was published in the Annals of the Bolus Herbarium (Vol. 2, pp. 1-14, 112-128, 163-184) in 1918 and included observations on the changing characteristics of the flora from month to month. The catalogue listed about 1000 species, of which 28 were new discoveries by her. According to I.B. Pole Evans* (1916) she probably made a more exhaustive collection of the flora of her district than had yet been attempted in any other part of South Africa at the time. Later her interest shifted to algae and fungi and she presented some 350 specimens collected around Kentani between 1911 and 1914 to the Mycological Herbarium in Pretoria. Seventy-seven species from her collection were enumerated by Pole Evans and A.M. Bottomley in the Annals of the Bolus Herbarium (1918). Her personal herbarium contained over 2000 specimens and was presented to the National Herbarium, Pretoria. Specimens collected by her are also in the herbarium of the Albany Museum, Grahamstown, the Bolus Herbarium and Compton Herbarium, Cape Town, the National Herbarium, Durban, the Bews Herbarium, Pietermaritzburg, and the herbarium of the Royal Botanical Gardens at Kew, London.
Miss Pegler also collected insects and other terrestrial invertebrates. In 1905 she sent various insects to Dr L.A. P?ringuey* at the South African Museum, followed the next year by some much valued Orthoptera and, with her brother-in-law, several collections of other land invertebrates. In 1907 she presented a series of weevils and snout beetles (family Curculionidae) and beetles of the family Trogossitidae, which infested the cones of cycads of the genus Encephalartos, including a new species which P?ringuey named after her. In 1909 she unraveled the life history of Chaliodes junodi, a moth of the family Psychidae, and presented the South African museum with duly labelled and mounted material that P?ringuey regarded as important. She also succeeded in raising gall midges of the family Cecidomylidae. She presented insects to the Albany Museum in 1908, and arachnids in 1913.
Her collecting activities were recognised by the Linnean Society of London in 1912, when she was elected an associate of the society - the first woman to be so honoured. The plant genus Peglera was named in her honour by H. Bolus, but it was subsequently renamed. Plant species named after her include Chironia peglerae, Olea peglerae, Schizoglossum peglerae, Eulophia peglerae and Aloe peglerae, and the fungi Puccinia pegleriana, Ravenalia peglerae, Uromyces peglerae and Ustilago peglerae. For the last seven years of her life she was a helpless invalid.