166 Schrader. 
the prevention of the access of males had been the determining factor 
in the failure to produce offspring previously. 
Although the evidence thus indicates plainly that unfertilized 
females do not give rise to offspring, the preponderance of females in 
random counts still remains to be explained. In this connection, the 
isolation experiments just mentioned are suggestive in the following 
way; Of the isolated larvae, fourteen in all were raised to maturity, 
and of these eight were females. The other six were normal males. 
As I have mentioned, sex could not be determined in the larvae at 
the time of isolation, and they represent a random choice. Therefore, 
in this case at least, the sex ratio is by no means as abnormal as in 
the counts made on free living individuals. 
These numbers are of course too small to admit of any definite 
conclusions. At the same time it was recognized that random counts 
made on free living mealy bugs were not much more reliable as regards 
the true sex ratio. Accordingly it was decided to investigate conditions 
of fertilization and sex ratios on mealy bugs under céntrol. 
That copulation occurs is beyond doubt, for it is not at all rare 
to observe it when the insects are watched under natural conditions. 
To bring it about in insects in captivity is more difficult and in only 
two cases was it accomplished. Normally, the female apparently con- 
tinues to feed during copulation. It is this trait which seems to be 
mainly responsible for failure to mate in captivity, for it is almost 
impossible to transfer a feeding female with a leaf or stem to a vial 
without disturbing her. Moreover males in captivity seldom react 
normally, but concentrate their efforts on trying to escape. But, as 
mentioned above, mating occurred twice in captivity; the pairs remaining 
in copula for 37 and 50 minutes respectively. In each case the female 
was apparently feeding during copulation. Aside from these observations, 
the presence of sperms in the oviducts furnishes good evidence that 
copulation occurs. 
In the light of this evidence it was assumed that all females 
which give rise to offspring have been fertilized. In isolating such 
females, individuals were selected which were just beginning to form 
the wooly sac that signalizes the laying of the first eggs. In the first 
breeding attempts, Coleus plants were used and no precaution taken 
to prevent escape of the active young larvae to the earth of the 
pot or sides of the chimney; in later attempts, Bryophyllum plants 
with submerged bases were utilized with much more success. Eggs 
