Ivar Oskar Herman Trägårdh, Swedish entomologist, was the son of Emil Trägårdh and his wife Eva Johanna Schwieler. He qualified as Doctor of Philosophy at the University of Uppsala in 1904 and was an assistant professor of entomology there from 1905. In 1910 he moved to the Central Institute for Agricultural Experiments as an assistant in the Entomology Department. In 1915 he became director of the Entomology Department of the State Forest Experimental Institute at Stockholm, a position he held to 1943, from 1921 with title Professor.
Trägårdh visited Egypt and Sudan in 1901 and KwaZulu-Natal during 1904-1905. His main aims during the latter visit were to study insects of the order Acarina (mites and ticks), and beetles that reside or breed in ant and termite nests (known as "guests"), although he also collected a variety of other small animals. He arrived at Durban early in November 1904 and settled at Stamford Hill, a railway station then north of the city. For the next three months he collected specimens in the vicinity, including the Durban Botanic Gardens, Pinetown, Verulam and Amanzimtoti. In the middle of February 1905 he moved to Pietermaritzburg, collecting in the neighbourhood of the town and at Howick and Richmond until the end of March. Next he went to Balgowan and Caversham, from where he visited Giants Castle in the Drakensberg on 10 April. After also visiting Van Reenen and Charlestown he returned to Pietermaritzburg early in May to prepare for an expedition to Zululand.
Late in May he travelled to the region east of Empangeni, from where he continued by ox wagon to the Mfolozi River just west of Mtubatuba. There he collected until late in July and then in the Dukuduku Forest until the middle of August. He next move to Lake Sibayi and with the village Mseleni as headquarters collected in the neighbourhood until late in October. After returning to Durban he departed for Sweden in the middle of November 1905.
Trägårdh described some groups of insects from his collection during the next few years, namely some of the mites and ticks (1906, 1907, 1909), beetles of the family Staphylinidae that live in termite nests (1907), some moths (1907), and two genera of flies (1908, 1909). Many other groups of animals from his collection were described by various other specialists, for example, reptiles and amphibians (Odhner, 1908), crustaceans (Lenz, 1912), beetles (Aurivillius, 1908), spiders and other Arachnidae (Lawrence, 1947), termites (Holmgren, 1913), earwigs (Burr, 1913), ants (Santschi, 1914, with biological notes by Trägårdh), and several more. He kept field journals, now in the Riksmuseum, Stockholm, that were used, with other material, by Brinck (1955) to work out his itinerary. His specimens are in the Riksmuseum and the Naturhistoriska Museet at Göteborg.
In addition to his work on the fauna of South Africa Trägårdh published (in Swedish and German) on the entomology of Sweden; the results of the Swedish zoological expedition to Egypt and the White Nile in 1901; the mites and ticks of Egypt and Sudan (1904); the mites and ticks collected by the Swedish South Polar Expedition (1908); the Arachnida of Greenland (1912); the entomological analysis of dying trees (1927); and Outlines of a new classification of the Mesostigmata (Acarina) based on comparative morphological data (1946).
