[semi-extrinsic]

The utilitarian in me chooses to attach value to insects according to how I perceive their value in the ecosystem. Bees, bumblebees, spiders etc. are useful, so I don't kill those. Houseflies, gnats, ticks, mosquitoes on the other hand, I have zero problems killing when they annoy me.

[Zancarius]

Same here. I avoid killing certain invertebrates on a pragmatic basis rather than one of morality. I'll happily ignore or relocate certain species of spiders simply because they'll keep the things I don't like in check while killing others that present a danger to myself or pets around the house (black widows). On the other hand, if you live in an area that's bordered by vast swaths of forest, it quickly becomes impractical to avoid having the occasional creepy-crawly get inside somewhere, and you soon learn that it's best to live and let live. That's how I was taught, at any rate.

Now, humorously, having had "pet" mantids before is a great way to eliminate nuisance insects around the house somewhat autonomously. Although it doesn't always quite work the way you may intend (they'll self-relocate or sometimes lose interest in prey items). ;)