Here, I immediately saw that the drain grate was "packed to the gills" with garbage and assorted debris. Decaying organic matter, especially the slimy build-up of film that coats the sides of drains, is a major attractant for certain pests to feed and breed. With these infestations, we commonly find drain flies, various small flies or "gnats," including moth flies, phorid flies, and fruit flies.
These flies deposit their eggs in the accumulated "gunk" of drains, and as adults, they shoot out from the drains to become a major annoyance to anyone working in the area. When drains are left uncleaned, these types of flies seem to come out of nowhere almost overnight, and with their breeding rates, a business can find itself with a major fly infestation in a matter of days.
I also recommend that the grates and drains be manually cleaned on a periodic basis with a wired brush and hot water. There's nothing like "elbow grease" to keep drains clean! You'll not only save yourself the headache of a clogged drain, but also avoid a fly infestation at the same time. Here, I cleaned the grate to eliminate this fertile breeding ground and I discussed with the manager ways to avoid a re-infestation of these annoying flies. To get rid of the flies, we use different bio-enzymatic cleaning products, like foaming agents and drain gels, that coat the drain and break down any accumulated organic matter.
Businesses, especially restaurants and other food-related establishments, must have sanitation and cleaning protocols in place to help prevent these infestations from happening in the first place.
During a routine servicing of one of our commercial accounts in Somerville, NJ, the manager informed me that staff had noticed small flies hovering around their slop sink, which was used for filling and emptying scrub pails and rinsing out mops filled with food debris. Sinks and drains are an often overlooked area in commercial facilities where pests breed. Often, the sinks and drains are not cleaned as often as thy should be.