1979] 
Chaffee & Tarter — Baetisca bajkovi 
59 
nymph, a female, was collected May 17. They were reared in the 
laboratory, and the adults emerged from May 2 to May 26. All 
subimagos emerged between 9:00 AM and 7:00 PM with the imagos 
emerging 13 to 25 hours later. 
Emergence data for other species of the genus Baetisca have been 
reported by other authors. Traver(1931) observed subimagos of B 
Carolina emerging between 8:00 AM and 5:30 PM with the imagos 
emerging 21 to 30 hours later. Berner (1955) observed subimago 
emergence of B. escambiensis between 9:30 AM and 1:30 PM and 
found the imagos emerging 40 to 44 hours later. Pescador and 
Peters (1974), in studying B. rogersi, observed subimagos emerging 
from the stream between 8:30 AM and 2:30 PM, while the labora¬ 
tory subimagos emerged between 10:00 AM and 8:30 PM The 
imagos emerged 12 to 30 hours later. 
Ovarian egg counts of 10 adult B. bajkovi females ranged from 
1508 to 3158 eggs per individual; the mean was 2361. Pescador and 
Peters (1974) reported that the egg counts for B. rogersi ranged from 
1500 to 2727 per individual, with the mean being 2168. 
The eggs of B. bajkovi are subspherical, and the average measure¬ 
ments were 0.15 X 0.19 mm. The eggs are greenish in color with an 
Table I Relative abundance of foregut contents of Baetisca bajkovi nymphs. Beech 
t-ork of Twelvepole Creek, Wayne County, West Virginia, 1976-77, 
Month 
Plant Detritus 
(%) 
Diatoms 
<%) 
Filamentous 
Algae (%) 
Mineral 
(%) 
July 
Aug. 
Sept. 
Oct. 
Nov. 
Dec. 
Jan. 
Feb. 
Mar. 
Apr. 
May 
66.7 
68.7 
71.3 
72.6 
70.4 
63.7 
57.8 
59.7 
63.2 
63.5 
59.8 
15.3 
12.9 
13.6 
13.2 
13.1 
1 1.8 
14.7 
19.3 
21.2 
23.5 
29.9 
4.1 
4.3 
2.7 
2 . 1 ' 
2.3 
2.9 
3.7 
2.8 
2.9 
1.2 
0.8 
13.9 
14.1 
12.4 
12.1 
14.2 
21.6 
23.8 
18.2 
12.7 
11.8 
9.5 
Mean 
65.3 
17.1 
2.7 
14.9 
