Mean difference between the two time periods of the study in the number of total species occurrence records among the 18 caddisfly families known from Indiana. Difference per species was calculated by subtracting the number of pre-1983 records from the number of post-2005 records and then dividing the result by the total number of records. These values were then averaged to determine the mean difference per family. A positive value signified a greater number of post-2005 records, whereas a negative value signified a greater number of pre-1983 records. Species occurrence data taken from Table 1.