44 
Psyche 
[Vol. 87 
southern Georgia and northern Florida. Pescador and Peters (1971) 
found extremely small nymphs of B. becki in Florida in September 
and nymphs collected in April emerged in May in the laboratory. 
Chaffee and Tarter (1979), in studying the life history of B. bajkovi in 
West Virginia, reported a univoltine life cycle. The smallest nymphs 
were found in July with the largest nymphs collected in the middle of 
May. Emergence occurred in May. Lehmkuhl (1972) studied the life 
cycle of B. bajkovi in Canada and found a one year life cycle. Eggs 
hatched in early September and mature nymphs emerged in the 
laboratory in June and July. Pescador and Peters (1974) observed a 
one year life cycle for B. rogersi in Florida. Nymphs were first found 
in September and emerged from April to July. Berner (1955) reported 
a different account for B. escambiensis. He collected mature nymphs 
in October from a Florida river and they emerged in the laboratory in 
November. 
Sex Ratio. —The expected 1:1 sex ratio was observed for B. 
berneri. Ninety-seven males and 100 females were collected during 
the study period. The difference was not significant at the 0.05 
confidence level. 
Foregut Analysis .—The foregut contents of the nymphs for the 
study period are given in Table 1. The main constituent was always 
detritus, with diatoms usually abundant, and filamentous algae 
present to a smaller degree. Most abundant diatoms were Synedra ' 
sp., Cymbella sp., Nitzschia sp., Navicula sp. and Gomphonema sp. 
Table 1. Relative abundance of foregut contents of Baetisca berneri nymphs from 
Laurel Fork, Mingo County, West Virginia. 
Filamentous 
Detritus Diatoms Algae No. of 
Month 
(%) 
(%) 
(%) 
Foreguts 
Sept. 
88.0 
8.0 
4.0 
5 
Oct. 
72.0 
26.(1 
2.0 
5 
Nov. 
70.0 
29.0 
1.0 
5 
Dec. 
64.0 
35.0 
1.0 
5 
Jan. 
75.0 
20.0 
5.0 
5 
Feb. 
87.0 
10.0 
3.0 
5 
Mar. 
86.0 
6.0 
6.0 
5 
Apr. 
68.0 
30.0 
2.0 
5 
May 
53.0 
36.0 
11.0 
5 
June 
80.0 
19.0 
1.0 
2 
Mean 
74.5 
22.0 
3.5 
47 
