356 
Psyche 
[Vol. 92 
Materials and Methods 
The study area is Panther Creek of the Gauley River in Nicholas 
County, West Virginia. The total length is 16 km and the area of the 
drainage basin is 42.2 km 2 (Reger, 1921). The study site is located 
along Route 39 at the community of Nettie, 22.7 m from the junc- 
tion of Route 19 at Summersville, West Virginia. The stream width 
averages 9 m and the water depth averages 46 cm. Substrate consists 
of sand, gravel, and small rocks. The most dominant species of the 
riparian forest are Hemlock, Tsuga canadensis (L.) Carr, and Rho- 
dodendron, Rhododendron maximum L. 
Monthly samples of nymphs were collected from October 1981 to 
September 1982. The substrate was disturbed by kicking the rocks 
and a hand dredge (mesh size, 0.75 mm 2 ) was held downstream to 
collect the nymphs. The nymphs were preserved in 70 percent 
ethanol. 
The water chemistry parameters were measured monthly with a 
Hach kit, Model AL-36-WR. Dissolved oxygen (mg/1), carbon 
dioxide (mg/1), alkalinity (mg/ 1 CaCCh), total hardness (mg/1 
CaCOs), and pH were recorded throughout the study period. Water 
temperature was recorded monthly with a Taylor thermometer 
placed about 5 cm below the surface of the water. 
Nymphal size classes were determined by length-frequency histo- 
grams arranged in 1 mm length groups. Body length from the tip of 
head (excluding genal spines) to the base of the caudal filament was 
measured to the nearest 0. 1 mm using an ocular micrometer. Males, 
females, and immatures were combined for the histogram analysis. 
Head capsule width, measured to the nearest 0.01 mm with an ocu- 
lar micrometer, was used as an index of growth. Monthly differ- 
ences in nymphal head capsule widths were used to calculate the 
mean, range and two standard errors of the mean. 
Five nymphs were randomly selected for each month for foregut 
analysis. The head was severed with microdissecting scissors and the 
thoracic shield was removed, thus exposing the foregut. The foregut 
was removed and its contents emptied onto a glass slide with an 
iodine solution as the mounting medium. The contents were exam- 
ined under a Bausch and Lomb (430X) dissecting microscope con- 
taining a Whipple ocular grid. Five grids were randomly selected for 
examination from each nymph. The percentage composition for 
