Not skilled in dream interpretation, but I would say it was just a bad dream. Of course, if arachnids and ants have some special meaning for you, they may mean something in your dream. Sometimes I too dream with invisible bad things, which I call ghosts.

Try to say a prayer before bed and when you lay down, close your eyes and repeat to yourself that you are protected by white light of devine protection and love, and visualize this dome of white light around you or your room or house. Happy dreams