Clerck was a commissioner in Stockholm for the greater part of his life. His interest in insects and spiders was aroused by Linnaeus’s lectures at Riddarhuset in Stockholm in 1737.

Picture of a cabinet holding some of Clerck's collection
Picture of a cabinet holding some of Clerck's collections

The collection owned by the Bergianus Foundation is the only one of Clerck’s natural-history collections still extant and, according to P.I. Persson (see source), one of the world’s oldest collections of insects preserved in its original condition. The collection was probably put together during 1758-1761 and it consists mainly of butterflies, beetles and spiders. The main focus is on Swedish insects, featuring around 1,000 species. Some of the insects are those called types (individual specimens that formed the basis of the naming of the species). The collection also includes a type specimen described by Linnaeus. 

The insects are arranged according to Linnaeus’s 10th edition of Systema naturae (1758) and include representatives of all the orders listed there. The collection was slightly enlarged by P.J. Bergius during the 18th century with insects such as tropical butterflies. The insects are placed into small compartments, attached to needles with finely decorated labels printed in copperplate.

Picture of a beetle from Clerck's collection
A beetle from Clerck's collection

1759 and 1764, respectively, Clerck published Icones Insectorum Rariorum, a volume of prints in two parts with beautiful handcoloured illustrations. Clerck named some of the insects on the prints but most of them were from Linnaeus’s descriptions. A large correspondence with Linnaeus reveals how he took part in the creation of Icones Insectorum Rariorum.

The spider collection

From a scientific point of view the spider collection is more important than the insect collection, since the former includes spiders described by Clerck in his work Svenska spindlar, a fundamental work in the classification of spiders. Though the book was published before Linnaeus’s 10th edition of Systema naturae (which is the basis of zoological nomenclature), Clerck’s names are valid according to a decision by the zoological nomenclature commission. As a result many of the spiders may be regarded as types.

Picture of a drawer of specimens from Clerck's collection
Drawer of specimens from Clerck's collection

According to Thorell (1859), there were originally 61 different species in the collection, 50 of them described by Clerck. Unfortunately there are only 32 species left today, of which 20 are described by Clerck. The main part had been ruined by noxious insects when, in the middle of the 19th century, Thorell discovered the untouched collection at the Bergius School of Gardening. He then had the specimens transferred to an alcoholic solution.

Source: Per Inge Persson, Carl Clercks insektsamling - en orörd samling från Linnés tid, Fauna och flora, 3-1978, Åke Holm, Om Carl Clercks spindelsamling, Fauna och flora, 5-1978.

Researchers may contact the Entomological Section at the Swedish Museum of Natural History for additional information about Clerck’s insect and spider collection.