MONA number

A MONA number (short for Moths of North America), or Hodges number after Ronald W. Hodges, is part of a numbering system for North American moths found north of Mexico in the Continental United States and Canada, as well as the island of Greenland. Introduced in 1983 by Hodges through the publication of "Check List of the Lepidoptera of America North of Mexico", the system began an ongoing numeration process in order to compile a list of the over 12,000 moths of North America north of Mexico. The system numbers moths within the same family close together for identification purposes. For example, the species "Epimartyria auricrinella" begins the numbering system at 0001 while "Epimartyria pardella" is numbered 0002. 
The system has become somewhat out of date since its inception for several reasons: 
Despite the issues above, the MONA system has remained popular with many websites and publications. It is the most popular numbering system used, largely replacing the older McDunnough Numbers system, while some published lists prefer to use other forms of compilation. The Moth Photographer's Group (MPG) at Mississippi State University actively monitors the expansive list of North American moths utilizing the MONA system and updates their checklists in accordance with publishings regarding changes and additions.