I feel no compunctions against killing parasitic things, but killing something for no better reason than it's in your proximity and you find it slightly annoying...well that's pretty childish.
Yes the world will survive if you remove an insect out of the population (as semi-large mammals we kill thousands completely unintentionally anyway) but if you're asking from a general morality standpoint, it seems like a choice between 2 options.
1) Kill something that is no harm to you.
2) Don't kill something that is no harm to you.
I'd think the latter is a little more enlightened. I also think people's growing sense of entitlement is bullshit, whether it's a justification to take something you didn't earn or whether it's doing whatever the fuck you want with the environment and its animal life "just because."
What's so great about humanity that makes us better? Look around, people are jerks!
