1974] 
Cooper — Boreus 
IOI 
minimal number — giving an average of 1.16 eggs per day per fe- 
male. The span of life of a female in such cultures was no more 
than four weeks. Were such a rate of laying maintained, a labora- 
tory-held female would be expected to lay about 32 eggs. At death, 
these females possess mature eggs in their ovaries, and so their poten- 
tial fecundity is higher than just estimated. These experiences are in 
line with those of Withycombe (1922) and Striibing (1950, 1958) 
for B. hyemalis , although their estimates that the average female lays 
a maximum of ten or so eggs in a lifetime I suspect to be much too 
low, considering the hazards of egg development, larval life, and the 
full two-year life cycle that must be met. Females of B. brumalis 
and B. nivoriundus which I have dissected at the close of their sea- 
sons in late February and March, still have a few mature eggs in 
their oviducts, as Striibing (1950) found for B. hyemalis but in 
some there is widespread involution of follicles within the ovarioles, 
the epithelium of the egg chambers incomplete, with many nuclei 
lying within large protoplasmic masses that simulate nurse cells. 
I have not witnessed oviposition, but Brauer (1855, see fig. 5, 
plate III), Aubrook (1939) and Marechal (1939) have described 
females, nearly perpendicular, with ovipositors buried in the soil. 
Only Svensson (1966), however, has witnessed actual oviposition 
(perhaps in B. westwoodi, as in Brauer’s case), and described the 
passage of the egg along the incomplete tube formed by the gona- 
pophyses and tergite-X. When the egg reaches the tip, the cerci are 
flexed ventrally, forcing the egg out onto the ventral surface of the 
gonapophyses. The egg is thereupon set down upon a moss stem, the 
whole process taking 3 to 4 minutes. It is to be noted that the female 
he observed laid 4 eggs within a period of two hours, lending some 
credence to the belief that females of Boreus may actually lay at least 
again as many eggs as Striibing estimates for the total production of 
a female B. hyemalis. Indeed Striibing (1950) records one clump 
of seven eggs, presumably laid by a single female. Certainly it is 
reasonable to assume that laboratory conditions are not ideal for ovi- 
position, and that such estimates do represent minima. 
Hatching 
Hatching occurred in laboratory samples of eggs of B. hyemalis 
within 8 to 10 days, at 8.8 °C, with about 50% mortality in Withy- 
combe’s (1922) series; in contrast, Striibing’s (1950) samples took 
from 3 weeks at approximately 2Q°C to as long as one and a half 
