1987] 
Henry & Busker — Green lacewings 
235 
sperm gets used up. As seen in Figs. 2 and 3 and Table 5, receptivity 
and re-mating are strongly correlated with dips in egg production, 
after which oviposition increases again to earlier levels. That the 
new surge of egg production is the result of and uses the new sperm 
is supported by two cases in which C. downesi females, originally 
mated to conspecifics, were later mated to C. plorabunda males; the 
new offspring were all Fi hybrids with typical Fi hybrid song 
phenotypes. 
The extent of polyandry in these insects reflects the interaction of 
three factors: rate of egg-laying, number of usable sperm transferred 
from the male, and oviposition lifespan. Our data indicate that 
maximal rates of egg-laying and maximum oviposition lifespan are 
approximately equivalent in all lacewing species studied to date. For 
example, females in peak condition produce 40-60 eggs per day; 
field-captured C. oculata, C. rufilabris, and C. harrisii show gener- 
ally higher values than laboratory-raised C. plorabunda or C. 
downesi (Table 1). Reports from the literature are more or less 
similar, ranging from the 20-40 eggs per night cited by Tassan et al. 
(1979) and Duelli (1981) for C. plorabunda, to the 48 per night 
mentioned by Ickert (1968) for C. perla. Similarly, oviposition dura- 
tion is approximately the same in both C. plorabunda and C. dow- 
nesi regardless of sperm availability (but is irretrievably diminished 
by senescence even in virgin females after two or at most three 
months; see Table 5). In contrast, the quantity of sperm contributed 
per copulation, interpolated from fecundity measured between mat- 
ings, shows high variance, and may be the principal determinant of 
polyandry. Females that chance to receive relatively little sperm 
with successive copulations will repeatedly recover sexual receptiv- 
ity and re-mate, whereas those receiving large amounts of sperm 
early in life will live out a significant or even dominant portion of 
their allotted reproductive lives depositing eggs fertilized by their 
first partners. Thus, the most frequently mated females like C and T 
of Table 3 and D of Table 4 produced only a few viable offspring 
from early inseminations. Female senescence can be seen most 
clearly when older, virgin females are mated to fresh males: invaria- 
bly, egg production is significantly less than that of younger ones. 
At least some of the wide variance in fecundity can be attributed to 
age differences at first copulation. We found little evidence to sup- 
port Philippe’s (1971) suggestion, concerning C. perla, that sperm 
from each copulation fertilizes the eggs produced during a relatively 
constant number of oviposition days: in his study, 24. 
