Ok and a few things about this:
No, we aren't really. The point is where do you want to draw the line and on what basis?
We draw the line when we are threatened. When our life is at stake we defend it the best way we know how. Its not about drawing a line and saying everything above this line we shouldn't kill, but everything below that line can be killed with impunity.
Not all of them, or insects or anything else, are predators or even parasites. The majority of them are little or no threat to us. Why should their lives be less valuable? Because they are less like us?
I did not say we could kill all insects. Only those that threaten us. It is not matter of value all life matters and should be respected. Its whether they pose a threat to our lives. If an insect merrily live their lives with no danger to us, I never suggested its ok to kill it.
And this issue with value. Let me state that I do not think all life have the same value. Of course not. I view your life as more valuavle than a wasp. If a child was drowning and a cat was drowning its obvious which one I'd run to save if I could only save one.
We may kill mosquitoes if they are in our vicinity and likely to spread malaria. But that is an exception because of a threat. It does not gives us a right to go kill any old insect.
So on that basis, there would be no difference between killing a harmless insect and killing a cow. In fact if the cow was being killed for a reason (food) and the insect was being killed just "because it's a bug" then perhaps the latter is more of a problem in ethical terms.
Its quite a connundrum depending on which way you look at it. Yes it is wrong to kill a bug for no reason. However to kill a cow for food I would support if there were no alternative food available in the particular situation. However to kill a cow for food when ample food stuff is available from sources that involve no suffering to any sentient creature I see as a greater ethical problem. The conscious level of a cow is far superior to that of a mosquito. The suffering that would be esperienced is far greater than a bug. The pain you cause is far greater.
Not sure if you watched the videos on the other thread but the killing of the cow if you compared it to the swatting of a bug will leave no doubt which is the more cruel. And all I say is that if it is not necessary, then why put an animal through it. It it is only to satisfy our taste buds then its more a case our our enjoyment as opposed to looking out for the well being of another creature.