Can I flush a spider down the toilet?

Yes, you can flush a spider down the toilet, as flushing is common method to dispose of spiders, though it may not always kill spider immediately and some spiders can survive in water for some time, but flushing carries them to sewage system where they are unlikely to return. Spiders can survive submerged in water for hours due to ability to close spiracles and trap air bubbles around body, so flushing alone may not kill instantly, but strong water flow and sewage system make survival and return unlikely. However, flushing is not most humane method if you want to avoid killing, and humane relocation by placing container over spider, sliding paper underneath, and releasing outdoors away from house is more humane and allows spider to continue beneficial role eating pests. If you flush spider, it will go to sewage treatment and die there. Flushing is acceptable for disposal and will not clog toilet as spiders are tiny, unlike large amounts of debris which should not be flushed. Some people worry spiders will crawl back up, but this is myth, as toilet plumbing and water traps prevent return, and spiders cannot swim up through water and pipes easily. So yes, you can flush spider down toilet, but consider humane relocation first if you want to avoid killing, and clean toilet after for hygiene, and regular cleaning and sealing cracks reduces spider encounters without needing to flush.