366 
Psyche 
[Vol. 92 
laboratory temperatures. A female subimago transformed in 24 
hours and 27 minutes, while a male subimago transformed in 20 
hours and 29 minutes. The male imago lived 48 hours. 
Subimaginal transformation data for other species of the genus 
Baetisca have been reported by other authors. Traver (1931) 
reported that the subimago stage of B. Carolina varied between 21 
and 24 hours under warm temperatures, while enduring up to 50 
hours during cold weather. Berner (1955) observed B. escambiensis 
subimagos transforming to imagos in 40 to 44 hours. Pescador and 
Peters (1974) reported that the duration of the subimaginal stage of 
B. rogersi ranged from 12 to 30 hours, averaging 21 hours and 21 
minutes. Morris et al. (1980) observed that the duration of the sub- 
imaginal stage of B. berneri was approximately 24 hours. Chaffee 
and Tarter (1979) reported that B. bajkovi (= lacustris ) subimagos 
transformed into imagos 13 to 25 hours later. 
Fecundity. Direct egg counts for ten B. Carolina adults ranged 
from 3271 to 5274 per individual, averaging 4280. A correlation 
coefficient between fecundity and body size was determined to be 
0.83 (Figure 5). Pescador and Peters (1974) reported egg counts 
from B. rogersi adults ranged from 1500 to 2727 per individual, 
averaging 2168. Morris et al. (1980) reported egg counts from B. 
berneri adults ranged from 1001 to 2375 per individual, averaging 
1899. Chaffee and Tarter (1979) reported egg counts from B. baj- 
kovi (= lacustris) adults ranged from 1508 to 3158 per individual, 
averaging 2361. 
Egg Size. The eggs of B. Carolina have an average diameter of 
0.17 mm. Individual eggs ranged from 0.14 to 0.21 mm. Egg diame- 
ter measurements from SEM photomicrographs showed ranges 
from 130 to 160 microns, averaging approximately 145 microns. 
Smith (1935) reported the egg diameter of B. Carolina and B. 
obesa to be 0.18 mm. Pescador and Peters (1974) reported that 
newly laid eggs of B. rogersi had a diameter of 0.1 to 0.2 mm, while 
mature eggs had a diameter of 0.2 to 0.3 mm. Morris et al. (1980) 
reported that eggs of B. berneri had an average diameter of 0.18 
mm. Chaffee and Tarter (1979) reported that eggs of B. bajkovi (= 
lacustris) had average measurements of 0.15 X 0.19 mm. 
Summary 
The ecological life history of the mayfly Baetisca Carolina Traver 
was studied in Panther Creek, Nicholas County, West Virginia, 
