Unknown to most people, there are little to no native Earthworms in New Jersey, particularly in the northern half of the State.  Following the last glaciation that ended approximately 21,000 years ago, most of northern NJ was covered in glaciers and ice and the remainder of the State was frozen and barren or tundra and all earthworm species were extirpated.  The ensuing forests and habitats developed without the influence of earthworms on their soils.  Upon European colonization, many species of European earthworms were introduced to North America and rapidly spread altering ecosystems as they expanded their range. 

More recently, Asian Earthworms have been introduced and accelerating the process of ecosystem change through their activities, even displacing the European invaders.  Some of the newer Asian Earthworms are far more aggressive invaders than the previous ones and changing our ecosystems at an accelerated rate.  This is particularly harmful to the detritus layer on the forest floor and any species of plants and wildlife that depend upon layers of organic materials on the soil surface. 

There are over 100 species of native Earthworms in North America that were largely restricted to unglaciated areas during the last ice age.  In NJ there has been little research into populations of Native Earthworms but the potential exists to find them in the NJ Pinelands and Southern New Jersey, particularly in bogs and wetland areas where they could have survived the cold climate of the time.