How to commit the perfect murder? (of spiders)

[anonyrat39]

My enlightened partner has forbidden me from murdering any innocent little creatures. But she won't handle them herself, so it's up to me to rehome them safely.

I am not a fan of anything remotely insect-ish so this has caused issues. I've agreed to be kind to any spiders that find their way into our house - they get chucked out the window.
But a few of them have decided their favourite place to live is right outside our front door at exactly 172cm height, which happens to fall perfectly at my eye height. Their webs are of course invisible, until I make the mistake of leaving the house and getting them literally inside my eyeballs. It also happens to be just above my partner's head height, so she doesn't really believe that it's an issue.

I can't rehome the outdoor ones because they have too many hiding spots and are impossible to catch.
I can't buy insect spray because this will be too obvious. I do however have a shed-full of many spray cans of household/automotive chemicals. I've tried a few with mixed success:
- Car de-icer was useless. They clearly didn't like it, but recovered fairly quickly.
- Kitchen cleaner spray worked, but required obscene amounts to finish them off, otherwise they'd eventually shake it off and get back to work. Literally drowning them in it did kill them, but left a suspicious puddle of kitchen cleaner on the driveway.
- Wonder wheels worked a treat. Practically instant death. But I'm worried about the overspray hitting the walls/door as I'm basically dousing our house in acid. When the walls start crumbling down this may raise suspicions.

So... What chemicals should I be using which will effectively kill them, without damaging property, and without staining or otherwise leaving evidence?

[anonyrat39]

Glass and card is what I do with the indoor ones. But these bds just lay their invisible strands of web at eye-level right outside the front door. I can see them waiting to ambush prey, but they usually hide in nooks and crannies watching their web from a distance, so glass and card is impossible.

I'm not trying to eliminate all spiders from the house. Just these ones at the front door. I need to know what to spray them with for instant death (like the wonder wheels, but without melting the house)

I had never seen a giant house spider in real life until we were moving away from our last house. I lifted up a floor lamp for disassembly, and saw thick web underneath the base. The monstrosity that crawled out is beyond description. I could actually hear its feet pattering along the floor. This thing was so big, that if you laid it end-to-end across a basketball court, the game would be canceled.