I was battling a fungus gnat problem on and off all through the winter.  They were getting into my bins where I was rooting cuttings.  I also had problems with the cuttings in humidity bins after they were cupped-up.  I lost quite a few cupped and rooted cuttings to the buggers.  I waged physical, biological, and eventually chemical warfare and seemed to get most under control...but there always seemed to be more.  Even after I had done everything to "break the cycle"...still they kept showing up in dribs and drabs.

Then I realized what was going on.  Last autumn I purchased a big bag of pine bark fines and another bag of pine bark nuggets so that I could pot up some plants over the winter.  I brought the bags inside into the basement near where I keep my figs and cuttings.  I got busy and never got around to potting up those figs.  I casually looked at the bags from time to time but never saw anything going on.  When the weather started turning nice I set my sights to potting up those figs I had put off --- and discovered that the pine bark fines were INFESTED with fungus gnats.  I mean, it was a full-on fungus gnat factory.  Even the nuggets, which were pretty dry, had gnats.

In retrospect I'm surprised that I didn't have more of a problem than I did.  I think for the most part they were content with the rotting pine bark and stayed in or near it.  But I guess occasionally some would take a journey and discover the tasty fig roots and cambium.

It was probably a "rookie mistake" on my part, so I'm posting it for other noobies to learn from too.

Jim

Jim;
You are by no means the first to encounter the little devils.  After all I have read and checked out on the net, pine bark seems to be the worst about introducing unwanted pests.  I know longer use any type of bark products on my trees period.  I was reading a thread last night about someone having a infestation and it turned out to be pine bark was the culprit.

Luckily I have not experienced to many problems with pest.  I leave the spiders alone and let them feast on the critters that wander around.  I get some strange looks from people going into my greenhouse.  The comments are equally as interesting.  Mind that I keep a watchful eye for Black Widows and they are disposed of.

I hope you have gotten rid of your colony and maybe you will not have to deal with them further.  Talk to you later...

Jim...I had a similar problem back during the winter...you couldn't read a news paper in the house without a gnat flying in your face...I think part of the problem was trying to do winter rooting in general...the windows are all closed, the heat is on, not much sunlight, little if any air flow(all adds up to "bugs")...so I'm going to discontinue all winter rooting this time around, and come March 1st. I will set up my root riot trays with T-5 lights, and within 30 to 40 days all rooting, and uppotting will be done and the trees(and bugs) will be outside where they can get fresh air and sunlight.    :)  :)