Re:Logic (Score 1)

I think you're looking at this too much from the point of view of the mosquito :)

The comparison you should probably be making is

Method 1:
a) Head out into the bush
b) Locate mosquito
c) Analyse gender of mosquito
d) Kill mosquito (if fulfils gender quota)
f) Repeat y times

with

Method 2:
a) Sort y genetically modified male mosquito larvae using automated mosquito-gonad camera/puffer thingy.
b) Wait for mosquito maturity
c) Release into wild

Given that you can be doing the next round of 2a whilst 2b is going on,
I would suspect that the chances of making y a significant proportion of x are hugely increased by method 2.