398 
Psyche 
[Vol. 92 
lower elevation for C. calif ornica. Allen and Tarter (1985) reported 
a two-year life cycle for Eccoptura xanthanes (formerly A. 
xanthanes). 
Growth. Population range diagrams (Figure 2) showed a wide 
range in head width. The largest female head width was 6.22 mm 
and occurred in October. The largest male head width was 5.07 mm 
and occurred in December. Females exhibited greater mean head 
widths than males (Figure 2). Males exhibited greatest growth in 
August (12%) and October (17%). Growth of females was greatest in 
August (28%) and January (13%). The smallest immatures were first 
collected in August and had their greatest growth in October (21%). 
Following emergence there was a marked decrease in mean head 
width for males in July (26%) and females in June (30%). The popu- 
lation showed a sharp decrease in mean head width in August 
(48%). This decrease coincided with the recruitment of a new age 
class. 
Calineuria calif ornica exhibited its greatest growth in spring when 
the stoneflies were still small (Siegfried and Knight, 1978). Growth 
declined with an increase in size. In this study C. californica showed 
an egg diapause and early instars were not collected until February. 
In laboratory growth studies with C. californica, the greatest growth 
occurred in the summer, while the least occurred in the winter 
(Heiman and Knight, 1975). 
The Janetschek method (Janetschek, 1967) indicated that A. caro- 
linensis naiads underwent 25 instars (Figure 3a and 3c). A general 
growth trend using gliding means is shown in Figure 3b. 
Sex ratio. A chi-square test was applied to 72 male and 152 
female A. carolinensis naiads. A significant deviation from the 
expected 1 : 1 ratio was observed at the 0.05 confidence level. 
Foregut analysis. Of the 144 foreguts examined, 78 (54%) con- 
tained food items. The highest percentage of empty foreguts occurred 
in April (75%). On a seasonal basis the percent of empty foreguts 
never exceeded 50 percent. 
Acroneuria carolinensis naiads were carnivorous, with Diptera (X 
= 6.4, %FO = 19.4), plecopterans (X = 1, %FO =15.9), ephemer- 
opterans (X = 1, %FO = 12.5) and trichopterans (X = 1.3, %FO = 
5.5) as the most important food items. Diptera was represented by 
larval chironomid midges. Plecopterans found in the foregut 
included members from the families Capniidae, Leutridae, Nem- 
