The most effective liquid bait for wasp traps is a liquid that is sweet smelling and contains either protein or sugar. The most successful liquid would be a sticky substance, such as honey or jam that has been diluted with water. Other bait options include fruit juice, soda or beer.
Wasps tend to be attracted to protein or sugar, depending on the current state of the colony. If a traditional liquid bait trap is not working, putting a piece of hamburger meat, canned tuna, or some canned dog or cat food in the liquid bait may help attract the wasps. It is important to remember that the protein bait must be deep enough in the liquid bait to capture the wasps that are attracted to it, but it must still be sticking out of the liquid to attract the wasps effectively.
Using a sticky substance, such as jam or honey, can also be a more helpful solution. The sticky texture helps attract the wasps, and it also traps the wasps in the container.
Fortunately, there is no need to worry about attracting bees instead of wasps. The sweet liquids, such as honey or jam, do not usually attract honey bees.