North Carolina Terrestrial Isopods 23 



marine waters into the land. They are quite common in such places as 

 the maritime drift line, the high or storm tide line of dead vegetation 

 and flotsam. 



Other species living at the North Carolina seashore are not exclu- 

 sive inhabitants there. A species such as Porcellio virgatus rarely lives at 

 the shoreline proper, but in leaf litter of nearby upland deciduous vege- 

 tation like the live oak forest of the Coastal Plain from North Carolina 

 to Mexico. It probably is less tolerant of brackish conditions than either 

 Miktoniscus halophilus or Porcellio scaber, which frequently are encoun- 

 tered on the shore itself and in reed grass litter of brackish swamps. 

 Occasionally they are encountered in the maritime drift line. However, 

 both species also live in upland habitats such as rotting logs and leaf 

 litter in the deciduous forests of river bottoms. Porcellio laevis has been 

 found under refuse on the sandy upper beaches of North Carolina, but 

 lives mainly around the bases of buildings and in refuse heaps in upland 

 locations. 



Most species of terrestrial isopods in North Carolina must be 

 included with the upland species. In general they are distributed accord- 

 ing to the moisture content of their habitats, which range from wet to 

 dry, and the moisture content of the habitat is determined by rainfall 

 and evaporation. They all live in decayed organic vegetation such as leaf 

 litter or decomposed parts of grasses, shrubs and deciduous trees. Iso- 

 pods are only rarely encountered in evergreen logs or evergreen leaf 

 litter. The numbers and types of moist retreats available when condi- 

 tions become seasonally warm and dry is critical to the local distribu- 

 tion of terrestrial isopods. Seasonal temperature extremes probably 

 have the greatest influence on regional distribution of particular species 

 in temperate locations such as North Carolina. The types and amounts 

 of organic matter also probably help determine if a particular species 

 occupies a particular habitat. No real measure of moisture or organic 

 content can be easily made, but certain subjective and qualitative 

 determinations are obvious from simple observation. A swamp is wet; a 

 shaded retreat in a refuse heap probably changes very little during the 

 day and only slightly during the season: a pulpy, rotted, moist log in a 

 shaded place provides a fairly constant environment the year around; 

 and organic matter such as leaf litter, dry to the touch and in the sun at 

 the side of a building, has a very low moisture content. The upland 

 species are briefly discussed here in order of habitat moisture content, 

 from wet to dry. 



The species of Ligidium need the most moisture and are present 

 only in habitats that are very wet with fresh water throughout the year. 

 They live at the edge of swamps and along the margins of permanent, 

 shaded streams. The detailed habitat preferences of each species of the 

 genus remains to be discovered, but in general L. bluer idgensis occurs in 



