The Fly Web UV light with glue board is an excellent fly/gnat catcher for the garage.
However their replacement bulb (EL22) is a little expensive. The bulb they sell you is actually a generic 9w fluorescent bulb made by Match Lighting,
Part number: CFS 9w BL350
The generic can be found cheaper. Be warned however I’ve ordered 4 packs of these bulbs directly from China on Ebay and the ones I ordered would not work.