HEAD WIDTH. MILLIMETERS 
1975 ] 
7 , 0 - 
6 . 0 - 
5 . 0 - 
4 . 0 - 
Tarterj Watkins , & Little — Nigronia 
(8 0 ) (5 9 ) (2 5 ) (4 7 ) 
1970 
83 
3 . 0 - 
2 . 0 - 
1 . 0 - 
1973 
0. fl- 
it I I 
FALL WINTER SPRING SUMMER 
1972 1973 1973 1973 
Figure 1. Seasonal size-frequencies of N. fasciatus larvae from Hisey 
Fork, Cabell Co., W. Va. Number of larvae is given in parentheses, and 
size classes are marked with year of hatching. 
