according to 12,000 Dreams interpreted by Gustavus Hindman Miller, to dream of spiders suggests being careful in one's labors, and good fortune. to see a spider forming its web foretells security in one's home. killing one symbolizes quarrels. if bitten by one, it suggests you will be the victim of unfaithfulness and suffering from enemies. dangerous contact signifies losing fortune.
according to Dreamstop.com, to dream of a rival signifies insecurity of one's own skills and talents.