The main reason behind spiders being one of the Halloweens' symbols is that they have a strong connection to witches together with black cats, rats, and crows. They are all believed to be evil companions of witches in medieval times. Another connection to Halloween is believed to be true in the haunted houses that, like every house, have spiders in them. Same as other creepy locations like graveyards, dungeons, and monster haunted caves all come fully stocked with spiderwebs and spiders themselves. And the main reason that spiders could be found in all of those places is simply that spiders like dark places to hide. A Halloween custom progress bar for YouTube with Halloween Spider Walking.