Regional Diversity of Insects in North America

Abstract

Data on the regional distribution in America north of Mexico of >3,550 insect species belonging to a representative sample of taxonomically relatively well-known groups, chiefly families, shows that more species occur in southern regions (71% of all species occur south of a line along state boundaries from the Arizona-California to Georgia-South Carolina borders) than in northern regions (50% of all species occur north of the Oregon-California to New England-New York borders). More species occur in western regions (73% only west of Manitoba, Canada, to Texas) than in eastern regions (56%). Texas-Oklahoma and Arizona-New Mexico contain the most species, followed by California, Georgia-Florida, and the mid-Atlantic region (New York and other states). The percentages of species recorded in different areas depend on the state of knowledge as well as on the geographical restriction of the groups. Knowledge of most groups of North American insects is inadequate for any meaningful distributional analysis of the sort carried out for these representative samples. Although about one-third of the species analyzed are relatively widespread, the many geographic differences confirm that quantifying biodiversity (especially for purposes of preservation or management) requires local or regional, and not just global, analyses.