The file "Density data.txt" contains the density of female, male, and juvenile Heterandria formosa during censuses of four populations (Moore Lake, Trout Pond, Wacissa River, and Wakulla Springs). The data file contains eight columns: Site (Moore Lake, Trout Pond, Wacissa River, and Wakulla Springs), Year (the year of the census from 2000 to 2009), throw (replicate trap throw number), females (the number of H. formosa females caught in the trap), males (the number of H. formosa males caught in the trap), immatures (the number of H. formosa juveniles caught in the trap), total adult density (the total number of H. formosa adults caught in the trap), and total density (the total number of H. formosa caught in the trap). The data were collected by Joseph Travis and Matthew Schrader. Questions regarding the data should be directed to Matthew Schrader: Schrader@bio.fsu.edu.