Dirk Cornelis Geijskes (16 May 1907 – 27 September 1985) was a Dutch biologist, ethnologist and curator. He was the first director of the Surinaams Museum.^[1] As a biologist, he specialised in dragonflies. He would lead many expeditions into the interior of Suriname. In 1967, he became curator at the Rijksmuseum van Natuurlijke Historie^[2] where he started the dragonfly collection. Geijskes is the author of 123 publications,^[2] and 25 species have been named after him.^[3]

Geijskes was born on 16 May 1907 in Kats, Netherlands.^[2] In 1927, he went to Leiden University to study biology.^[4] In 1929, he travelled to Trinidad to study dragonflies which would become his speciality.^[5] Next, he went to the University of Basel, and in 1935 obtained his doctorate magna cum laude^[1][2] for a thesis on the fauna and ecology of the Swiss Jura.^[6] In 1936, he first described Brevipalpus phoenicis which was later discovered to be the main factor for Citrus leprosis disease.^[7][8]

In 1938, Geijskes started to work as an entomologist for the Landbouwproefstation (Experimental agricultural station) in Suriname.^[9] During his stay in Suriname, Geijskes would lead many expeditions into the interior.^[10] In 1939, he went to the Litany River to study the poisoned arrows of the Wayana people.^[10][11] In 1941, he participated in the Paroe Savanna expedition to the Tiriyó people.^[10][12] In 1943, he embarked on the Coppename River expedition during which the Tafelberg was climbed for the first time.^[11] In 1948 and 1949, he led an expedition from the coastal area across the Nassau Mountains.^[11] The expedition collected about 10,000 specimens including 1,500 butterflies.^[13]

In 1954, Geijskes would become government biologist and the first director of the Surinaams Museum.^[2] In 1958, he led an expedition to the Tafelberg with Rudi Kappel to examine the savannah around the mountain, and investigate whether an airstrip could be built there.^[14] The successful construction of an airstrip led to Operation Grasshopper in 1959 which mapped the natural resources in the interior.^[15]

On 2 May 1965, Geijskes returned for the Netherlands,^[16] and in 1967 started to work as curator at the Rijksmuseum van Natuurlijke Historie (nowadays Naturalis).^[2] where he started the dragonfly collection. In 2015, the collection contained 20,000 species.^[3] In the Netherlands, he also would become a member of the Royal Netherlands Academy of Arts and Sciences in 1959 but he resigned in 1965.^[17] He would also become and editor of the New West Indian Guide.^[9]

Geijskes died on 27 September 1985 in Leiden, at the age of 78.^[18]

Upon return to the Netherlands, Geijskes became officer in the Order of Orange Nassau. He was awarded a bronze medal by the Royal Dutch Geographical Society.^[9]

Geijskes is the author of 123 publications,^[2] and 25 species have been named after him.^[3] In 1970, the dragonfly genus Lauromacromia was created by Geijskes.^[19] In 2011, it held six species.^[20]