Why would someone suggest killing a spider rather than throwing it out of the window?

Well, i prefer not to kill them but I'm quite afraid of them.  There is therefore a risk that, when the spider realises I'm trying to catch it, it runs about uncontrollably or suddenly falls from the ceiling, leaving me in a bit of a panic (Good grief!  Is it in my hair or on my clothes now?).  If i'm panicking and rushing around trying to catch it, there's a chance i'll accidentally kill it anyway, either by stepping on it or by failure of one of the helpful devices I'm using to trap it (e.g. I had one of those little trapdoor boxes on a stick but the trapdoor often came down at the wrong time, guillotining the spider.  I've also got one of those brush devices but it's hard to use in corners or along edges - precisely where the spider will tend to go - and the spider might end up crushed or injured).  Basically I try very hard not to kill them but I find it all quite frustrating because it never seems like a case of just "throwing it out of a window" (how do i catch it, what do i pick it up with, how to a make sure it's not dropped on the floor on my way to the window, leaving me wondering where it's gone etc).  Baths are easy with a little toilet paper ladder to enable the spider to escape, but then, of course, there's the horrible feeling that the spider is now "at large" and this process can also take some time - annoying if someone's waiting for a bath. 

Maybe, then, Friend B has experienced some of this and therefore just goes straight to killing it.  I think it's a shame but I understand it.  :(     

I'm terrified of spider, they make me feel physically sick, I can use the spider catcher thing we've got to catch some, but not all, sometimes I've had to suck them up with the hoover, 3 grown women all holding a hoover hose like firemen at a major incident, trying to get up the courage to get near enough to get it sucked up the hoover and then having to run screaming from the room after, all with pounding hearts and out of breath.

I can't stay in the same room as big spiders, I didn't have a bath for weeks, once just strip washes in the kitchen sink, I've stayed of of my bedroom and slept elsewhere and the living room.

I'm terrified of spider, they make me feel physically sick, I can use the spider catcher thing we've got to catch some, but not all, sometimes I've had to suck them up with the hoover, 3 grown women all holding a hoover hose like firemen at a major incident, trying to get up the courage to get near enough to get it sucked up the hoover and then having to run screaming from the room after, all with pounding hearts and out of breath.

I can't stay in the same room as big spiders, I didn't have a bath for weeks, once just strip washes in the kitchen sink, I've stayed of of my bedroom and slept elsewhere and the living room.

Martin said:

The house spiders and giant house spiders, if you put them outside will probably get in again.

I've noticed this before and now take them for a little walk outside before releasing them. In the spider catcher device, not on a lead! :)

The house spiders and giant house spiders, if you put them outside will probably get in again. In Spring and Autumn the males are searching for females, who tend to stay in one place. I try to trap them, but if they are in an awkward place, I use the hoover. I once heard one of the giant house spiders before I saw it, it was walking over a piece of paper. I think they are too large for me to be comfortable sharing a room with.

Me too. When I had cats they enjoyed stalking and killing spiders for me. Unfortunately I have had no spider killing pets to protect me for many years now.

I used to always try to trap and release them but they often escaped from me and then I'd be terrified because I didn't know where they were. One day when I saw a huge one on the floor I stamped on it in fear, and since then I haven't been so scared of them. They can stay outside or take their chances if they come into my home.