Alien Invasion

Popular culture has portrayed alien invasion as utilising ray guns and teeth in their aggressive attempt to overcome the human species. This seems more a reflection of humans themselves.

 

My theory is that the aliens may already be here and 'invading' in their own way. Who are the aliens? Slugs. Eating our plants and dead stuff. Except on the planet they came from they hadn't planned on salt and pellets. Or birds.