What is a humane way of getting rid of flies?

I don't want to use harsh chemicals since I have a dog that snoops around the patio area that is infested. I have a trashcan that seems to be the main source of attraction (I put the dog's waste in there after we go out for a walk) but they do not seem to go away once I throw out the trash. Any suggestions?

The best way to get rid of flies is to eliminate all the sources of odours that are attracting them...organic matter and the bacteria that feeds off of it.

Keep in mind that flies can detect odours at levels that us humans can not.

A thorough cleaning of the can and lid is in order and the best way to clean the can out is
1) Empty of everything ( obviously)
2) Add 1 cup bleach and a couple of gallons of water (rinsing the sides and lid down as you fill the can)
3) Get a toilet brush that you've purchased just for the purpose and scrub the insides of the can with the bleach water.
4) Put the lid on the can and allow it to sit for awhile ( at least 15 minutes)
5) Discard the water and leave lid off until the can is completely dried...preferably in the sun.

(It would be a GREAT idea if you wore gloves and safety glasses ...or at least glasses of some sort...when you do this, BTW)

Note: bleach is not good for living things, so discarding the solution on your lawn will not be good for it....or the worms that help till the ground.

However, it can go down the drain (like wash water from the laundry). Eventually it breaks down to plain table salt and water. Bleach is the best choice because it will oxidize many organic components that will cause odours as well as kill the bacteria causing them.

While bleach can be mixed with some cleaners like "Pinesol" and most dish detergents, NEVER mix bleach with ammonia, cleaners that contain ammonia or amines ( Windex or Mr. Clean), other cleaners containing acids (like "LimeAway") or other oxidizers ("color safe bleach").

use a large propane blow torch

The neatest way is to build a fly trap. Use any container, preferably transparent, and make a cone-shaped lid out of insect screen, with the apex pointing inwards. Leave a hole just big enough for the flies to fit through. Put their favourite food inside the container. They will quickly find their way in, but rarely get out.

A swatter... and use plastic garbage bags for everything. When you walk your dog, take along some zip-loc sandwich size bags in your pocket so you can use it as a glove to retrieve your dog's deposits - then zip it shut. This should help prevent flies from being attracted to it in the trash can.

Double or triple bag that dog poop! You need to toss your trash can out or wash it out. There are probably maggots in there, larvae stage of flies. Or move your trash can far far far away.