In ancient Japanese folklore, spiders are seen as protectors that ward off evil spirits and bring positive energy, especially in the morning. They know when it's going to be a sunny day. So if you see a spider in the morning, you should thank it for bringing welcoming weather news and you shouldn't kill it.
But seeing a spider at night is a bad omen. Spiders which love darkness are harbingers of bad news, yet they should not be killed.
If you kill a spider at night, it won't be able to bring the good news of a sunny day! Killing a spider at night will bring you bad luck, especially if it's a big spider. Big spiders bring greater positive energy, so killing them allows the negative energy to remain.
Spiders spend time and energy building intricate webs to trap prey, then sit in the middle waiting for their dinner. It's worth noting that sometimes they must wait a very long time, and we can learn the art of patience from their behaviour. If the web is broken, they will rebuild it, and that teaches us perseverance.
Spiders are much more useful than just forecasting the weather.
Some spiders are nocturnal so the spider you see in the morning might not be the one you see at night. But the auspicious superstitions about spiders are a useful way to remind us never to kill them.
They might not look cute and their dusty webs can be an unsightly nuisance, but on balance, their pest control is so useful in reducing the more unpleasant insects which infest our homes. And they do this for free - no need for us to buy chemical pesticides. Spiders help to maintain ecological balance in ecosystems
If you are arachnophobic, the bad vibes you get when seeing a spider only makes your arachnophobia worse. You can control that fear by spending a bit of learning about the spider's positive ecological contributions. That will be an excellent start to permanently overcoming your fear.