Worst episode of the series this far, 'Bugs' didn't make anything, no scary impact, already seen story, a story that is made for big and long movies, all that "houses built on the old Indian graveyard" kind of thing that used to work sometimes, but it definitely didn't work out for 'Supernatural' series.
Unless you're scared of mass numbers of insects (on a TV show) and you like to watch 40 minutes of the most boring investigations of 'Supernatural' so far, then you should give this episode a shot, otherwise feel free to say that the first season had only 21 episodes like i said.