Charles De Geer

Charles De Geer (30 January 1720 – 7 March 1778) was an entomologist, industrialist, civil servant and book collector. He came from a prominent Swedish-Dutch family. He was born in Sweden, spent most of his childhood and youth in the Dutch Republic, moved back to Sweden at the age of 18 and would thereafter spend the rest of his life in Sweden. Upon his return to Sweden, he took over the management of the ironworks of Lövstabruk. He was a successful businessman and with time became one of the richest men in Sweden, head of an early industry employing around 3,000 people. He also had a successful civic career, became Chamberlain to the King and was elevated to the rank of friherre (baron) in 1773.

De Geer had developed an interest in natural history and particularly entomology when he was still young. After his return to Sweden, his interest transformed into a serious scientific pursuit. He was elected a member of the Royal Swedish Academy of Sciences in 1739 and a corresponding member of the French Academy of Sciences in 1748. He published his main work on entomology, Mémoires pour servir de l'histoire des insectes, in French in eight volumes between 1752 and 1778. In it, he provided descriptions of the behaviour of over 1,400 insect species.

De Geer was also a book collector. His library served his research, but also contained books on many other subjects in several languages. The inclusion of a number of sumptuous and rare works, including a collection of rare music scores, indicate that it was also intended as a way to raise De Geer's social status as an aristocratic collector. Since 1986 it belongs to Uppsala University Library, but most of it is still kept in situ in Lövstabruk, in the pavilion De Geer constructed to house the library.