Insecticide

What are the ethical guidelines for killing insects in your house? I'm conflicted as I ponder the consequences of each decision. Technically it's my house and this could be construed as an invasion. I have the right to control my environment on my property, right?
But like all issues of life and death, it's complicated. If I leave a door or window open, shouldn't I share responsibility for their entrance? Do I differentiate between flying and crawling ones? Suppose some are on the insect endangered species list? Could I be fined or imprisoned for squashing one?
Witnesses might be a problem. People embellish things to get attention. What if a delivery person spotted a flattened mosquito or bloodied earthworm in my living room? Friends and family would protect me, although since I never invite anyone over, that's a moot point.
Do insects have families in any real sense? I'm wondering about possible retribution, being covered with red ants as I sleep. How many of us have had the opportunity to kill a praying mantis, but felt it would be sacrilegious? A case can be made that insects are also God's children. Or possibly the spawn of Satan. These are split second value judgments. It's not like capturing mice who are covered with germs. Germs are not insects. If you lay out a germ's options, it will at least listen and decide.
I admit to getting satisfaction from snatching insects right out of the air or blowing them off the table. Less you think I'm an insect bully, I am quite gentle with butterflies. Unless they get stuck in my pancake syrup. Then it's Last Rites, over and out, bring in the casket. If a roach gets into my stuff, or worse, into my bathtub, I get all Swat Team Fevered. I stun them with spray, tie them to tiny chairs and viciously make them watch old Fabio commercials. It's called Situational Ethics.