Question
Have have annoying flying black bugs living in my dark food pantry.  I have made sure all food is closed up.  I will kill these little bugs that look like big gnats or bugs that fly around lights when it is dark outside and then I find small little cocoons, where they have been laying eggs and then I am finding little larvas or worms crawling around and then here come the bugs again!  What is going on I am completely grossed out!

Answer
actually it sounds like complete metamorphosis of a fly species. sounds like a fruit fly or similar small fly maggot problem. completly remove all things from the pantry. wipe all containers down w/rubbing alcohol. do the same w/the walls & shelves(underside also). wait an hour or 2 and then clean everthing w/hot water & soap. turn the lite off and do that also.
go to a local hardware store and tell them your problem.  they should help you pick some appropriate fly traps to make sure no adults can reenter the pantry. remember those long curly sticky flytrap hangers. they do work against the adult flying stage of flies. as a last result or if you give up look up an exterminator in the yellow pages. they guaranttee their work.
good luck
rick