Do you need to kill that spider? Do you need to kill those ants? Do you need to pluck that flower? Can that weed not have a chance?
A bee enters through the window, and someone reaches for a newspaper or a spray. Why is that the automatic reaction? Bees (and their less adorable insect brethren, wasps) often need a hand to find small windows, but otherwise very much want to leave your house.
Even ‘house flies’ want to be free of the constraint of indoors.
Ants may wander through the house, but (usually) only to look for food. Keep your kitchen clean and they will stop visiting you.
Slugs like to come out (or in?) at night; a thin line of crushed eggshells and salt in front of your doors can bar their way.
Spiders may well wish to co-habit with you, but they dislike the light and can be shooed back behind the bookshelf with a waft of a magazine (they dislike draughts). Spiders do no harm, much good, and do not choose to crawl over you in your bed at night – what a ridiculous urban myth that is – what a waste of time it would be for the spider!
Personally, I do put spiders outside; the small ones I can have in my hand, the large ones I collect in a glass.
Who are these people who kill every bug on sight? What harm can an ant do if it touches your skin? OK, there are some bugs that can bite and even some that can squirt acid, but I’m in the UK, and there are no bugs that threaten us here. If you live in a more dangerous country, then knowing the difference between a harmful and harmless plant / insect / spider / scorpion seems very sensible.
There is much killing and death in nature, and I do not speak of such – I only mean to highlight the everyday bizarre and unthinking taking of life.
Be happy in your living surroundings – imagine the alternative (a space station?) and its obscene sterile environment.