Homemade wasp traps are built using a two-litre drink bottle that has had the top cut off and inverted. Wasps are attracted to the bait inside the trap and crawl into the inverted neck of the bottle. Once they are inside, they can't fly out of the narrow opening. Eventually they fall to the bottom and die. You can make your own bait for your wasp trap. It's best to start setting traps out early in the spring, when the queens are foraging.
Bait your trap with canned dog food in spring and early summer. Wasps are carnivorous, so they are attracted to the meat in the dog food. Dog food also has the advantage of not attracting bees, though it does attract flies. Place a couple of heaping spoonfuls of dog food in the trap before you attach the inverted top. The disadvantage of dog food is that you can't add more once the trap is assembled.
Bait the trap with fruit juice later in the summer when wasps are foraging for nectar. Mix the fruit juice with a few drops of dish soap. The soap reduces the surface tension, which makes the wasps drown faster. Fill the trap about a third full of the mixture. If the fruit juice dries out before the trap is full of wasps, just pour some more through the inverted neck of the bottle.
Place the trap away from areas of activity, or you run the risk of attracting wasps to people. Check the trap every few days.
Discard the trap once it becomes full of wasps. Don't open it, or you may release wasps that are still alive. Just toss it in the trash and make a new one.