Nothing wrong with eating a half of a bug.
Just puree it
This is simply ignorant. It is just as assur to eat a half a bug as it is to eat an entire bug. The difference between them is only that there is malkos for an entire bug no matter the size while if it is not complete it will need to be a kezayis to be chayav malkos.
What you may be confusing is that an incomplete bug can sometimes be batel. That would not allow one to intentionally cut the bug for it to be batel. Also, it is not certain that pureeing the fruit will also cut the bug. What you may have heard in this regard is that one may puree and then rely on a sfek sfeka that maybe there was no bug and even if there is maybe it is cut up. There are times when one may even do this lichatchila but it is certainly not as simple as you are making it.