As you may have noticed from this website or elsewhere, bumble bees are sometimes referred to as Bombus followed by another name. Scientists realized a long time ago that it is best if we have a single universal system for naming organisms, including a genus name (plural: genera) and a species name. In order for the names to be universal, the names are by convention Latin or Greek forms of words, and the same scientific name is used in all different languages of the world. Even through time a scientific name does not change other than in light of new discoveries.
Novel scientific names can only be proposed in scientific journals and books and include a description to separate the new species from other similar species. So how did the local bumble bees get their names? The first of our bumble bees to receive any attention from scientists were Bombus pensylvanicus and B. griseocollis. Those two species came into the hands of the Swedish Baron Charles de Geer (1720 1778) who, as many other contemporary noblemen, maintained a natural history cabinet with insects from around the world. In 1773 he published the third volume of a book series entitled "Memoires pour servir a l'histoire des insectes" and herein described two new species of bumble bees received from M. Acrelius in "Pensylvanie" (=Pennsylvania). His description was accompanied with a drawing of the actual specimen he described.
B. pensylvanicus from "Memoires pour servir a l'histoire des insectes".
Original book kindly provided from the Rare Book & Manuscript Library, University of Illinois
These very early discoveries, descriptions, and illustrations are what we still refer to when we write about B. pensylvanicus and B. griseocollis today. The other local species of bumble bees were described through the 19th century by the Danish Johann Christian Fabricius (1798), the Philadelphian Ezra Townsend Cresson (1863 and 1872), and the Englishman Frederick Smith (1854). The last local species to be discovered was B. auricomus, described by our local Charles Robertson (1903), a passionate naturalist and BeeSpotter from Carlinville, Illinois.
No bumble bee species new to science have been found in Illinois since then, although other kinds of bees new to science have been described from our local area, including Andrena illini described by the scientists LaBerge and Bouseman from the Illinois Natural History Survey in 1979.
Michener, C.D. (2007) The bees of the world, second edition Johns Hopkins university press, Baltimore.