Well I'm not for sure when you say "laying around" means you dug the soil up or what but when you get some soil. If you wanna be sure that theres nothing in it like bugs or stuff, basically a method to sterilize your soil is to bake wet soil in a large pot at 200 degrees for 30 to 40 minutes. You should try this for your next grow attempt and see if those bugs still stick their heads out .