J.P. Cregoe became a member of the South African Philosophical Society in 1895 and was still listed as a member in 1906, but no longer in 1907. From about 1895 he was closely associated with the Eastern Province Naturalists' Society. He made several contributions of insects and arachnids to the South African Museum and to the British Museum (Natural History) between 1895 and 1903, from Cape Town, Johannesburg, Durban, Barberton, Port Elizabeth, and the Zoutpansberg. For example, during 1897 he presented some rare coleoptera from around Durban to the South African Museum, followed the next year by a snake, four lizards, a toad and, with H.A. Fry*, a small but valuable collection of Arachnidae from the Transvaal. In 1899 he presented Coleoptera, mainly small ones, to the South African Museum from Johannesburg, including 10 species new to the museum's collections. These were followed by insects of various orders from Natal in 1901, and some Coleoptera from the Zoutpansberg district and a collection of spiders from Natal in 1902.
Meanwhile Cregoe may have settled in Bulawayo, Rhodesia (now Zimbabwe), for on 18 May 1899 one J.P. Cregoe was elected a member of the first council of the newly founded Rhodesia Scientific Association in that city. At a meeting of the Association in January 1900 he exhibited "cetonids" (presumably the sub-family Cetoniinae, fruit and flower chafers), and further Coleoptera the next month. His interests extended to other invertebrates, for at the March 1900 meeting he exhibited land and fresh water shells. During 1900 he was elected as honorary secretary of the Association, but he died before the end of his first year in office, that is, before 3 July 1901. He is identified as John P. Cregoe in the announcement of his death.
However, there was also a James P. Cregoe of Johannesburg, who was listed as a member of the Geological Society of South Africa in 1899. He can be identified as James Plomer Cregoe, who was involved in a legal dispute about claims between 1895 and 1906. John P. and James P. were two different persons (as John died in 1901). It is possible that John did all the collecting, but it is also possible that James did some or all of the collecting in South Africa while John may have limited his activities to Zimbabwe.