Flies Around the Trash Can: Where They Breed and How to Stop Them

Trash can flies come from eggs laid inside the cart. The University of Missouri Extension describes the house fly as laying its eggs on wet, decaying organic matter such as moist garbage, and a trash cart in a warm climate is a steady supply of exactly that.

The adult fly you see circling the lid is following the smell. What it is looking for is a place to lay eggs: a puddle of leaked juice in the base channel, a smear of food on the inside wall, a split bag that soaked the bottom. Utah State University Extension lists house fly eggs as laid on decaying organic matter, especially garbage and dumpsters.

House flies breed fast enough that a cart can produce a new generation between a few collections. The University of Missouri Extension puts the house fly life cycle, egg to adult, at about 14 days, depending on temperature, and warmer weather moves it along.

In South Florida the temperature rarely slows that down for long, which is why a fly problem at the bin can seem to appear overnight.

If the base is already moving, the flies have finished their part. Our guide to maggots in a trash can covers what to do with those.

There are flies around a trash can that gets emptied every week because the garbage truck takes the bags, not the residue. The liquid that leaked to the bottom and the film stuck to the walls stay behind after collection, and that is the part a fly cares about.

Emptying the cart feels like resetting it. To a fly, an emptied cart with a wet base is still a nursery, just with more room.

The University of Missouri Extension makes the same point in plain terms: garbage cans should have tight-fitting lids and should be cleaned whenever waste accumulates in the bottom or clings to the sides. Emptying is not the same as cleaning.

To get rid of flies in a trash can, take away the place they breed. Sprays and swatters deal with the adults you can see; the next generation is in the residue, so the residue has to go.

Five steps, in the order that matters:

1. 01Bag every wet thing. Food scraps, meat trays, anything that drips. Tie the bag closed before it goes in the cart. Most of the residue in a cart started as one leaking bag.
2. 02Close the lid, every time. A lid propped open by an overfull bag is an open door.
3. 03Clean the residue out of the base. The base channel and the underside of the lid are where the wet film collects, and they are the places a garden hose misses. This is the step that actually stops the breeding.
4. 04Keep the cart out of the full afternoon sun where you can. A cart baking on the driveway turns its contents faster.
5. 05Clean it on collection day, when it is empty. An empty cart is the only one you can clean all the way to the bottom. Waiting a day means new bags go straight onto old residue.

That is also how The BinFather schedules visits: we clean on your collection day, after the truck has emptied the cart. We wash the inside with heated, pressurized water, including the base channel and the lid, then apply a deodorizing treatment so there is less smell left to draw the next fly. The dirty water goes into a collection tank on our truck or trailer — nothing is left on your property.

Fly sprays and traps reduce the adult flies around a trash can, but they do not stop the next generation, because they do nothing about the residue the eggs were laid in. They treat the adults, and the adults are the end of the cycle, not the start.

Utah State University Extension's house fly advice for the bin is sanitation: keep trash cans and garbage areas clean and free of odor, and close the lids. A clean cart with a shut lid gives a fly nothing to land for.

Flies around a trash can are worse in the South Florida summer, because heat speeds up both the rotting of residue and the fly's life cycle, and afternoon rain keeps everything in the cart wet. Winter here slows flies down without stopping them.

We cover the season in detail in summer vs winter trash can cleaning in Florida. The short of it: the wet months are when a monthly clean earns its keep, because a cart cleaned every month never builds enough residue to raise a generation of flies.