Fungus Gnats in Ductwork?

Hi;


I know this may strange but I suspect that I have a fungus gnat problem in my HVAC system. I have fungus gnats in my house during the warm months when the A/C is in the cooling mode. They are gone during the winter when my heat pump is in heat. I have been dealing with them for as long as my current duct work (16 years) but they seem worse now. I recently figured out the ductwork as I put a clean light trap in two unused bedrooms with the doors closed and the A/C off for two days. No bugs in the traps. Turn the A/C on and with the doors still closed I got two in one bedroom and four in the other, within about an hour. I inspected my air handler and other than some minor mold crud nothing. Have a UV light in the underside of the evap coil to keep it clean.

No house plants at all. Already tried the bleach under the sinks. Even had a plumber smoke my drain systems looking for any problems. No joy. Don't own a dishwasher either. Bug bombing the house only works for a day or so.

I posted on an HVAC forum and they tell me I need an exterminator but I suspect that I need a Ductwork specialist. Any of you ever see a duct work infestation?